Rufus, Richard of Cornwall

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(b. c. 1200, d. c. 1260), natural philosophy, physics, matter theory, psychology.

A founder of the Western tradition of natural philosophy, Rufus was among the first teachers of Aristotelian natural philosophy at the University of Paris in the 1230s, when Paris was the major university. He flourished in the period when Aristotle’s physics, chemistry (On Generation and Corruption and Meteorology), and psychology (On the Soul) went from being forbidden subjects to being required courses. Rufus’s natural philosophy consisted in the first instance of commentaries on Aristotle. Chiefly indebted to the Islamic philosopher Averroes (Ibn Rushd) for his knowledge of the Aristotelian tradition, Rufus was a critical thinker who supplemented or replaced accounts by Aristotle and Averroes he considered inadequate. Rufus gave up being an arts master, entered the Franciscan order, and left Paris in 1238. Most of the rest of his career was spent at Oxford University. When lecturing on theology at Oxford, Rufus cited views stated in his lectures on Aristotle as the opinions of a secular author; this confirms that these lectures were delivered in Paris before Rufus became a Franciscan.

Rediscovery As with many medieval thinkers, Rufus was for centuries an author without known works: Some works were lost; others survived only in anonymous copies. The last medieval citation of Rufus by name dates from 1350, and the first of his works to be rediscovered was reported in 1926; the first of his philosophical works, in 1950; the first of his contributions to natural philosophy, in 1996. The attribution of these works to Rufus remained in the early 2000s controversial.

The process of rediscovery was serendipitous. Rufus’s lectures on physics, chemistry, and psychology, for example, are known because they are preserved in a collection of his philosophical works copied at Oxford. Sometimes called the “Ave Maria Aristotle Quires,” this collection was sold to Amplonius Ratingk de Berka in the fifteenth century not as a collection of Rufus works but of works by Walter Burley (c. 1275–1344), one of Amplonius’s favorite authors. This attribution prompted the president of the Burley Society to examine Rufus’s Physics at Erfurt in 1983. Because the quires were copied in about 1240, and Burley did not publish much before 1300, it was immediately obvious that Burley was not the author.

Establishing the attribution to Rufus took a decade longer. The construction of the quires themselves showed that Rufus’s physics and metaphysics belonged together; the metaphysics was copied on folios 1–44, followed by the lectures on physics, chemistry, and psychology on folios 45–87, and the metaphysics and physics were indexed together in the thirteenth century. That connection was fortunate, since the metaphysics lectures were ascribed to Richard Rufus by a rubricator of Vatican lat. 4538, another copy of the same work. Also, two clear references from the metaphysics lectures to the physics lectures were verified. Finally, shared views on substantial change, instantaneous transmutation, and weak identity provided internal evidence for the attribution.

Projectile Motion Following Aristotle, Rufus equates science (scientia) with the conclusion of a logical demonstration. As a science teacher he undertakes first to elucidate the deductive structure of Aristotle’s writing, asking and answering questions about such topics as whether Aristotle’s claims were consistent, whether his assumptions were justified, and whether the alternatives he enumerated were exhaustive. Rufus also asks whether Aristotle’s conclusions are consistent with Christian doctrine and with experience.

Rufus’s treatment of projectile motion is an influential example of his methods. Projectile motion poses a challenge for a basic Aristotelian principle (Physics 8.4–5.255b30–256a8): everything that moves is moved by something, either naturally by itself or violently by another mover. Aristotle himself poses the question in Physics 8, chapter 10: “How can things thrown continue to move when their mover is not in contact with them?” A thrown stone obviously does not move itself, so this is violent motion, but a projectile has no contact with the thrower after motion begins. How can that be? Aristotle explains projectile motion as a result of the action of the thrower on the medium through which the projectile travels (Physics8.4.267a3–4). In air, for example, the thrower moves the first layer of the air, which moves the second layer, and so on, carrying the projectile along with it.

Unless it is assumed that air, and the motion that occurs in it, is discrete not continuous, this explanation is just as inconsistent with the basic Aristotelian principle as the phenomenon it explains, because it suggests that a body, air, moves itself when not in contact with a mover. Averroes glosses this explanation by suggesting that air can move itself on account of its fluidity. Rufus rejects both accounts, because “bodies as bodies cannot essentially move themselves.” He substitutes a hylomorphic (form acting on matter) explanation more consistent with the basic principles of Aristotelian natural philosophy (In Physicam Aristotelis 8.3.1, pp. 238–241).

Rufus claims that the form of air determines the density of its parts. The violent action of the thrower divides the air’s parts unnaturally so that they are farther apart than their nature (form) dictates. In response to being violently pushed apart, the air’s nature moving accidentally reinclines those parts, pushing them back almost as hard as the original mover. Now denser than their nature dictates, the parts are again reinclined so that they are farther apart than their nature dictates, and so on. This successive expansion and compression produces motion in the medium that gradually decreases in amplitude. Similar to that of the strings of a lyre when plucked, this motion partly accounts for the movement of projectiles in the medium, according to Rufus. Because this reinclination is a response to violent motion, it is self-limiting and does not persist.

Rufus cautions, however, that experience (signa) shows that the action of the medium cannot by itself account for projectile motion. If the action of the medium were the entire explanation, projectiles could not travel at different speeds in the same medium or pass each other traveling in different directions. So Rufus postulates an action of the thrower on the projectile itself. The thrower produces an impression that acts mechanically by transposing the parts of the projectile such that it moves contrary to its nature for a time. The impression is “some quality, form, or something” else in the projectile itself. Presumably Rufus hesitates about calling this impression a form, because since it results from violent motion, it weakens continuously. Encountering the same problem, Francis of Appignano postulated a third kind of form, intermediate between permanent and successive forms (1968, p.180).

Here Rufus has corrected the account of the action of the medium on the projectile by making it more consistent with the basic principles of Aristotelian natural philosophy, and he has supplemented the account to conform to experience. Roger Bacon responds by accepting the correction but rejecting the supplement (In Physicam Aristotelis8, Opera Hactenus Inedita I 13: 338). He rejects the supplement because he views it as an attempt to substitute virtual contact for substantial contact between mover and moved object. Thomas Aquinas rejects theories such as Rufus’s because impressions act internally on the projectile; positing them seems to make projectile motion a case of natural rather than violent motion (On the Heavens, 3.7.5–6). Rufus’s supplement was more successful later: A similar explanation postulating that the thrower acts both on the medium and on the projectile is advanced in the fourteenth century by Francis of Appignano. Moreover, in the fifteenth century not only were views like Rufus’s generally adopted, they were even attributed to Aristotle; Galileo was in the minority when he claimed that Aristotle held the contrary view (Maier, 1968, pp. 298–305).

Theory of Mixture For Aristotelians, bodies are composed of homoeomeries, like-parted substances such as blood and bone, mercury and sulfur. Homoeomeries in turn may be produced by mixing the four Aristotelian elements (earth, water, air, and fire) directly, but more frequently complex homoeomeries result from combining less complex homoeomeries. In Latin, an Aristotelian homoeomery is called a mixtum; here, this entry will speak of a mixt and call the process of forming a mixt mixture. The modern counterpart of an Aristotelian mixt is a chemical compound, because it is a uniform, stable substance with a nature different from the elements composing it. However, Aristotelian mixture is carefully defined in a manner radically different from modern chemical theory, so it is better to speak of mixture, even though the ingredients in an Aristotelian mixt are bound together rather than physically juxtaposed.

Like many topics in Aristotelian natural philosophy, the science of mixture starts with a puzzle—namely, that mixture seems impossible (On Generation and Corruption 1.10.327b1–6). The mixt has to contain at least two ingredients; so if one or more is destroyed in the process, the result is not a mixt. Yet, if the ingredients are not transformed in the process, there is an aggregate, not a unified substance. As if this dilemma were not tough enough, Aristotle also stipulates:

  1. The ingredients of the mixt must be in equilibrium;
  2. When a mixt is destroyed, its ingredients must be recoverable;
  3. The mixt must be uniform, like-parted, however much it is divided;
  4. Nonetheless, it must also be less unified than elements;
  5. The qualities of the ingredients must be altered in the process of mixture.

Aristotle himself supplies the solution to his puzzle: The ingredients cannot be fully actualized in a mixt; they must exist only in potential. The problem for his successors was to specify what kind of potential would permit mixture and yet satisfy the requirements Aristotle had stipulated.

Avicenna (Ibn Sina) and Averroes proposed the two most famous descriptions of the potential of the substantial forms of the ingredients in a mixt: fixed forms (formae fixae) and fractured forms (formae fractae). Avicenna’s fixed forms retain their substantial identity despite their primary qualities having been altered in the course of mixture. By contrast, when they lose their characteristic primary qualities, such as heat, Averroes’s forms are broken or diminished. According to Averroes, elemental forms are like accidental forms, and unlike most substantial forms, can be diminished.

Rufus responds by revising Averroes’s views to better account for the Aristotelian distinction between substance and accidents. Rufus begins by criticizing Averroes: Because the forms of the ingredients are lost or broken in the process of mixture, Averroes cannot escape the first horn of the dilemma; also it is difficult to see how the ingredients could be recovered. Focusing on ontology, Rufus also objects that a change in the qualities of a substance cannot cause a change in the substance. Quite the contrary, substantial change produces accidental chance, since Aristotelian substances are prior to Aristotelian accidents. But, of course, fixed forms also will not do, since mixing fixed forms would produce juxtaposition, not a unified mixt.

Rufus’s solution is to claim that the ingredients in a mixt are in accidental potential, a kindl of proximate potential. Ingredients in accidental potential have all their essential properties, but an external obstacle prevents them from expressing their full natures. Specifically, each of the ingredients interferes with the actualization of the other ingredients. Because they balance each other, the mixt is stable. But because one element in the mixt, fire, is far removed from its natural place, it is susceptible to weakening, and hence the mixt is less unified than the elements themselves and can be destroyed. In the process of generating or destroying mixts, the qualities of their ingredients are altered. Rufus considers this solution a version of Averroes’s account, since he like Averroes supposes that elemental forms in a mixt are diminished in comparison with fully actualized substantial forms.

Perception Aristotelian psychology describes perception as a process of assimilation. When, for example, one sees something green, one’s sense of sight gets to be like the green object perceived. In a famous simile from On the Soul(2.12.424a17–24), Aristotle compares perception to the act of pressing a signet ring on wax. The impression made by a gold signet ring is just the same as the impression made by an iron ring with the same pattern. The wax receives not the ring’s material, but the pattern on it. Similarly, in perception the sense receives form, not matter. Just how that happens is a subject of debate among interpreters of Aristotelian psychology even in the early twenty-first century. Does the eye jelly, for example, physically turn green when one sees something green? Or is what is received spiritual, so that the eye is altered not by becoming green, but by seeing green?

Rufus considers the physical alternative absurd, since the eye would have to become not just green, but also simultaneously red; there would even be a bathtub in our sensitive soul when we perceived a bathtub (Contra Averroem Q312.82va). So Rufus turns to Averroes’s great commentary on Aristotle’s On the Soul (2.67, p. 232). Averroes says that sensible objects in physical bodies are material, but in the medium and the sense they are spiritual; they have to be spiritual in a medium such as air, because air simultaneously transmits many and contrary colors to the senses. Averroes solves the contraries problem two ways: He stipulates that color, for example, as perceived, has a spiritual nature different from its material nature in external objects, and he also stipulates that the recipient of sensory impressions must be barren: a color receptor has to be colorless.

Rufus adopted Averroes’s description of “spiritual beings,” but eventually he came to prefer the description species-being, where a species is a form maximally similar to the external form, an express similitude as defined by Augustine. Also, though Averroes holds that such spiritual beings differ by definition and essence, Rufus argues that they must be essentially the same; otherwise, the proximate objects of perception would differ too much from the distal objections of perception. Since, however, they have a different ontological status or being, they cannot be the same in every respect. According to Rufus, species and the objects they image for people differ by name and definition—a phrase Aristotle uses to describe unambiguous terms in his Metaphysics (4.11.1006b18)—though they are the same by essence (Dissertatio in Metaphysicam Aristotelis 6, Vatican, lat. 4538, fol. 44ra; Sententia Oxoniensis, proem, Balliol College 62, fol. 9vb). Ultimately, Rufus claims that because species-being does not belong to Aristotle’s categories of substance and accident, they are not natural forms (Speculum animae 2, Erfurt Q312, fol. 108ra-rb). Sensible species are not substances because they are not self-subsistent; neither are they accidents, because they are not found in the substances that give rise to them.

This refinement furnished Rufus with the solution to another problem: self-perception. Self-perception is a problem on account of the so-called barrenness stipulation. Averroes stipulates that the soul lacks all material forms and thus can receive all spiritual forms. But the soul itself is a spiritual not a material form. So how can the soul receive knowledge of itself? Or if it can apprehend itself, how can it be the kind of form Aristotle says it is? According to Aristotle, the soul is assimilated to and so apprehends all things, but what apprehends everything can have no form if people take the barrenness condition seriously (In De anima Aristotelis3.3.Q1, Madrid, BN 3314, fol. 81va; Speculum animae5, Erfurt Q312, fol. 109vb). Having distinguished species-being, Rufus has an answer to that question, albeit a controversial answer: he says that the soul comprehends itself in just the same way it apprehends or perceives other things, by abstracting and subsequently apprehending its own species, which belongs to a different category from its substantial form (In De anima Aristotelis3.3.Q1, Madrid BN 3314, fol. 81va-82ra; Contra Averroem 1.12, Erfurt Q312, fol. 83vb, Speculum animae 5, Erfurt Q312, fol. 119rb).

Augustine’s influence on Rufus’s theories of perception was not limited to supplying the definition of species that Rufus employed. Initially, under Augustine’s influence, Rufus held that species do not act directly on the soul, but only excite the soul, which responds to that stimulus by considering a preexisting similitude within itself (In De anima Aristotelis2.12.Q2, Madrid BN, fol. 76rb). This is Rufus’s first reply to the objection based on the Neoplatonic claim that the less noble cannot act on the more noble. He modifies his reply to this objection subsequently in his Against Averroes[Contra Averroem] and in his Dissertation on Aristotle’s Metaphysics. According to the Dissertation, the receiver is less noble than the species it receives not in itself, but insofar as it is in potential to receive the species (Dissertation on Aristotle’s Metaphysics 4, V4538.26vb). Rufus seemingly found this reply adequate, since he did not consider the objection further in subsequent works. Rather, in his theological works and in his Mirror of the Soul[Speculum anima], he states Aristotle’s view that sensible objects act on the soul (Sententia Oxoniensis proem, Balliol College 62, fol. 9vb). So this is a case where the influence of Christian theology declined over time.

Intellectual Development Rufus entered the Franciscan Order in 1238 as a Parisian Master of Arts and moved to Oxford, where he studied theology. He lectured on Peter Lombard’s Sentences at Oxford around 1250 and at Paris around 1253. He returned to Oxford as the Franciscan Master of Theology around 1256.

As a secular master, Rufus responded creatively to many problems in Aristotelian natural philosophy. As a theologian, he continued to address many of the same problems. He was deeply indebted to Averroes from whom he took not only an interpretative approach to Aristotle but also a set of problems. Rufus criticizes Averroes on both theological and philosophical grounds, most importantly regarding the nature of divine knowledge, the nature of matter, and the cause of individuation. But Rufus was never disrespectful; he considered even Averroes’s views on the material intellect to be reasonable (Contra Averroem 1, Q312.81vb).

Rufus was fully prepared to revise Aristotle’s scientific claims based on the testimony of experience and the demands of Christian belief. His critical approach set an agenda for his successors. When he first encountered Aristotle’s natural philosophy, he was confident that there would be no problem reconciling it with Christian belief. Under the influence of Robert Grosseteste, however, Rufus came to see the extent of the disagreement. On the question of the eternity of the world, for example, he condemned those who sought to excuse Aristotle in his Dissertation. However, as we have seen in his work on perception, sometimes Rufus preferred a standard Aristotelian to a Christian, Augustinian account.

At Paris, Roger Bacon succeeded Rufus as a lecturer. Bacon often adopted Rufus’s approach to problems in Aristotelian science, but equally often he rejected them. Both lecturers exercised considerable influence on the subsequent commentary tradition, and their differences explain in part the richness of the tradition. The excitement of Rufus’s approach and Bacon’s response was vital to the rapid introduction of Aristotelian natural philosophy in the West.


A complete list of Rufus’s works is available from


Contra Averroem. Erfurt: Universitäts Bibliothek, Dep. Erf., CA.Q.312, folios 81va–86rb; Prague: Archiv Prazskeho Hradu, Ms. 1437, fol. 33ra–36vb. An individual folio, for example folio 81va, is cited below as Q312.81va.

De mutatione. Toulouse, Bibl. mun. 737, folio 158ra–va. Edited by R. Plevano. “Richard Rufus of Cornwall and Geoffrey of Aspall: Two Questions on the Instant of Change.” Medioevo 19 (1993): 167–232. Includes a good discussion of Rufus on the instant of change.

Dissertatio in Metaphysicam Aristotelis. Vatican lat. 4538. Salamanca: Biblioteca Universidad 2322, folios 72rb–129rb; Erfurt: Universitäts Bibliothek, Dep. Erf., CA. Q.290, folios 1ra–40vb. Excerpts published by Donati, 2003, Gál, 1950, and Noone, 1987. Title based on the incipit for a work also known as Scriptum super Metaphysicam Aristotelis and Commentarius in Metaphysicam Aristotelis. Further discussion of the title is found below in the entry on Noone, 1987.

Expositio libri De anima. Madrid, 1952. In Obras filosóficas, vol. 3, edited by Manuel Alonso. Madrid: Consejo Superior de Investigaciones Cientificas, 1952. An incomplete edition based on a single manuscript, frequently mistranscribed. Better partial editions available at the Web site cited above.

In Analytica posteriora Aristotelis, ed. Rega Wood. Erfurt, Universitäts Bibliothek, Dep. Erf., CA. Q312, folios 29va–32vb. Available from

In De anima Aristotelis. Florence: Biblioteca Nazionale, Conv. Soppr. G.4.853, folios 193ra–222va; Madrid: Biblioteca Nacional 3314, folios 68ra–89rb. Erfurt: Universitäts Bibliothek, Dep. Erf., CA. Q.312, folios 19rb–20va, 22va–28vb. The Erfurt redaction is available from,, and

In De generatione et corruptione Aristotelis. Erfurt, Universitäts Bibliothek, Dep. Erf., CA. Q.312, folios 14ra–19ra. The texts cited above mostly come from 1.6.2–3 (16va–17ra) and 2.4.3 (18ra–rb), which includes Rufus’s comparison of his views with those of Averroes. The texts are quoted and discussed in greater detail in Wood and Weisberg, 2004.

In Physicam Aristotelis. Edited by Rega Wood. Auctores britannici medii aevi, XVI. Oxford: Oxford University Press, 2003. The introduction includes a description of the “Ave Maria Aristotle Quires” and describes the old foliation mentioned in the section on rediscovery. Because Amplonius rebound the “Quires,” the modern foliation differs from the thirteenth-century foliation.

Sententia Oxoniensis. Oxford: Balliol College, folio 62 (year unknown).

Speculum animae. Erfurt: Universitäts Bibliothek, Dep. Erf., CA. Q.312, folios 107va–110rb; Assisi, Bibl. Sacro Convento 138, folios 281va–284rb.


Amerini, Fabrizio. “Utrum inhaerentia sit de essentia accidentis: Francis of Marchia and the Debate on the Nature of Accidents.” Vivarium 44 (2006): 95–150. Discusses the history of the medieval controversy on the nature of accidents.

Aristotle. Complete Works of Aristotle: The Revised Oxford Translation, 2 vols. Edited by Jonathan Barnes. Princeton, NJ: Princeton University Press, 1984. The texts cited for the five Aristotelian stipulations regarding mixture are, respectively: 1 (GC 1.10.328a28–30), 2 (GC 1.10.327b23–30), 3 (GC 1.10.328a9–11), 4 (GC 2.7.334b20–21), and 5 (GC 1.10.328a31–35).

Augustinus. De diversis quaestionibus octoginta tribus, edited by Almut Mutzenbecher. In Corpus Christianorum, Series Latina, 44A. Turnhout: Brepols, 1975. Published as Eighty-three Different Questions, translated by David L. Mosher. Washington, DC: Catholic University of America Press, 1982. An important source for Rufus’s definition of sensible and intelligible species.

———. De trinitate. Edited by William Mountain and F. Glorie. In Corpus Christianorum, Series Latina, 50A. Turnhout: Brepols, 1975. In The Works of St. Augustine, translated by Edmund Hill, edited by John E. Rotelle. Brooklyn, NY: New City Press, 1990. Another source for Rufus on sensible species.

Averroes. Commentarium magnum in Aristotelis De anima. Edited by F. Stuart Crawford. Cambridge, MA: Medieval Academy of America, 1953.

Bacon, Roger. Compendium of the Study of Theology. Edited and translated by Thomas S. Maloney. Leiden: Brill, 1988. Describes Rufus’s fame among the foolish multitude, considered mad by the wise, and censured at Paris.

———. Questiones supra libros octo Physicorum Aristotelis. Opera Hactenus Inedita 13. Edited by Ferdinand M. Delorme and R. Steele. Oxford: Clarendon Press, 1935. First response to many of Richard Rufus’s views.

Brams, Josef. “Le premier commentaire médiéval sur le ‘Traité de l’âme’ de Aristote?” Recherches de théologie et philosophie médiévales 68 (2001): 213–227. Provides information about the Florentine manuscript G.4.853 of In De anima Aristotelis. Suggests that we consider a late note in G.4.853 ascribing the work to Alexander.

Brown, Stephen F. “The Eternity of the World Discussion at Early Oxford.” In Mensch und Natur im Mittelalter, edited by A. Zimmermann and A. Speer. Berlin: Walter de Gruyter, 1991. Includes an excerpt from Rufus’s Oxford theology lectures, Sent. II d. 1 q. 1, Balliol 62, f. 103–105.

Donati, Silvia. “Un nuovo testimone dello Scriptum super Metaphysicam di Riccardo Rufo di Cornwall (Salamanca, Bibl. Univ. Ms. 2322).” Bulletin de philosophie médiévale 45 (2003): 31–60. Reports the discovery of a new manuscript of Dissertatio in Metaphysicam Aristotelis (DMet), also known as Scriptum super Metaphysicam.

———. “The Anonymous Commentary on the Physics in Erfurt, Cod. Amplon. Q. 312 and Richard Rufus of Cornwall.” Recherches de philosophie et théologie médiévale s 72 (2005): 232–362. Questions the authenticity of In Physicam Aristotelis and In De anima Aristotelis.

Francis of Marchia. In Sent. In Zwei Grundprobleme der scholastischen Naturphilosophie: Das Problem der intensiven Grösse; Die Impetustheorie, edited by Anneliese Maier. 3rd ed. Rome: Edizioni di Storia e Letteratura, 1968. Presents a theory of projectile motion similar to Richard Rufus's. Cites Bonaventure and Richard on a form intermediate between a permanent and successive that lasts for a short time.

Gál, G. “Commentarius in ‘Metaphysicam’ Aristotelis cod. Vat. lat. 4538 fons doctrinae Richardi Rufi.” Archivum franciscanum historicum 43 (1950): 209–242. First published discussion of DMet, which Auguste Pelzer discovered. Gál described DMet, using the title Commentarius, as an important source for the Sententia Oxoniensis. Rufus’s references to DMet as the work of a secular author misled Gál. His excellent article provides a useful guide to the commentary and the views expressed in it, lists the titles of the questions, and publishes excerpts.

Hackett, Jeremiah. “Roger Bacon and the Reception of Aristotle in the Thirteenth Century.” In Albertus Magnus und die Anfänge der Aristoteles-Rezeption im lateinischen Mittelalter: Von Richardus Rufus bis zu Franciscus de Mayronis, edited by Ludger Honnefelder, Rega Wood, Mechthild Dreyer, et al. Münster: Aschendorff Verlag, 2005. Notes Roger Bacon’s references to Rufus as an Averroist.

Karger, Elizabeth. “Richard Rufus on Naming Substances.” Medieval Philosophy and Theology 7 (1998): 51–67. On the development of Rufus’s metaphysical views, “a striking example of ‘Christian Aristotelianism.’” Shows that Rufus began by carefully reconstructing Aristotelian naming theory in MMet.

———. “Richard Rufus’s Account of Substantial Transmutation.” Medioevo 27 (2002): 165–189. Explains Rufus’s theory of substantial transformation, which relies on a notion of active potency and provides a quasi-Aristotelian explanation of Augustine’s seminal reasons. Mentions the authors who accepted the view (Bonaventure, Albert the Great, and Roger Marston) and those who rejected it (Aquinas, Henry of Ghent, and John Duns Scotus).

Little, Andrew G. “The Franciscan School at Oxford in the Thirteenth Century.” Archivum franciscanum historicum 19 (1926): 803–874. Essential historical information.

Lloyd, A. C. “The Principle that the Cause Is Greater than Its Effect.” Phronesis 21 (1976): 145–156. A discussion of a Neoplatonic principle that strongly influenced thirteenth-century thinkers.

Long, R. J. “The First Oxford Debate on the Eternity of the World.” Recherches de philosophie et théologie médiévales LXV (1998): 54–98. On Rufus’s defense of Robert Grosseteste and his attack on the views stated in Richard Fishacre’s theology lectures.

Maier, A. Zwei Grundprobleme der scholastischen Naturphilosophie: Das Problem der intensiven Grösse; Die Impetustheorie. Edited by Anneliese Maier. 3rd ed. Rome: Edizioni di Storia e Letteratura, 1968.

Marsh, Adam. “Epistolae.” In Monumenta franciscana, vol. 2, Rerum britannicarum medii aevi scriptores. London: Longman, 1858. Marsh’s correspondence describes Rufus and his decision to return to Paris c. 1253.

Needham, Paul. “Duhem’s Theory of Mixture in the Light of the Stoic Challenge to the Aristotelian Conception.” Studies in History and Philosophy of Science 33 (2002): 685–708. Introduces the practice of referring to mixts (p. 687).

Noone, Timothy B. “An Edition and Study of the Scriptum super Metaphysicam, Bk. 12, Dist. 2. A Work Attributed to Richard Rufus of Cornwall.” PhD diss., University of Toronto, 1987. Prints excerpts of DMet’s commentary on lambda (pp. 167–334) and describes the work as a reportatio “coming from the pen of auditores in a classroom” (p. 64). Note that the term “Scriptum” normally refers not to a reportatio but to a redaction revised and corrected by its author. For this reason a less controversial title based on the work’s incipit was chosen.

———. “Richard Rufus of Cornwall and the Authorship of the Scriptum super Metaphysicam.” Franciscan Studies 49 (1989): 55–91. Reproduces information from the dissertation. Questions the attribution of Sententia Oxoniensis (SOx) to Rufus.

———. “Richard Rufus on Creation, Divine Immutability, and Future Contingency in the Scriptum super Metaphysicam.” Documenti e studi sulla tradizione filosofica medievale 4 (1993): 1–23. A discussion of texts from DMet.

———. “Roger Bacon and Richard Rufus on Aristotle's Metaphysics. A Search for the Grounds of Disagreement.” Vivarium 35 (1997): 251–265.

———. “Prefatory Note. Richard Rufus, Scriptum super Metaphysicam.” Bulletin de philosophie médiévale 44 (2002): 95–96. Disputes the use of the title “Dissertatio in Metaphysicam,” drawn from the work’s incipit, on the grounds that a titulus on the first folio begins with the words: “Scriptum super Metaphysicam magistri ricardi.” This titulus, like the colophon at the end of the work that begins “Explicit tractatus metaphysicus magistri” (V4538.102va), is not by the scribe who copied the text itself.

Pelster, Franz F. “Der älteste Sentenzenkommentar aus der Oxforder Franziskanerschule. Ein Beitrag zur Geschichte des theologischen Lehrbetriebs an der Oxforder Universität.” Scholastik 1 (1926): 50–80. Announces the first major rediscovery, the Oxford theology lectures, SOx. Indicates that Rufus was the first Oxford bachelor to lecture on Lombard’s Sentences.

———. “Neue Schriften des englischen Franziskaners Richardus Rufus von Cornwall (um 1250).” Scholastik 8 (1933): 561–568, 9 (1934): 256–264. Announces the discovery of “De intellectu divino” and other minor works in Assisi 138.

Plevano, R. “Richard Rufus of Cornwall and Geoffrey of Aspall: Two Questions on the Instant of Change.” Medioevo 19 (1993): 167–232. A good discussion of Rufus on the instant of change, based on a minor work. Edits Toulouse 737 f.158.

———. “Two British Masters and the Instant of Change.” In Aristotle in Britain during the Middle Ages: Proceedings of the International Conference at Cambridge, 8–11 April 1994, Organised by the Société Internationale pour l’Étude de la Philosophie Médiévale, edited by J. Marenbon. Turnhout: Brepols, 1996. Compares Rufus with Geoffrey of Aspall.

Raedts, Peter. Richard Rufus of Cornwall and the Tradition of Oxford Theology. Oxford: Clarendon Press, 1987. Denies the attribution of Dissertatio in Metaphysicam to Rufus. Establishes the authenticity of SPar. Compares Rufus with Robert Grosseteste.

Thomas of Eccleston. Tractatus de adventu fratrum minorum in Angliam. Edited by Andrew G. Little. Manchester, U.K.: Manchester University Press, 1951. Describes Rufus’s entry into the order, the appearance of Francis in a dream warning against scholarly pride, and Rufus’s position as the fifth Franciscan Master of Theology at Oxford.

Trifogli, Cecelia. “The Unicity of Time in XIIIth Century Natural Philosophy.” In Was ist Philosophie im Mittelalter? Qu’est-ce que la philosophie au moyen âge? What Is Philosophy in the Middle Ages? Akten des X. internationalen Kongresses für mittelalterliche Philosophie der Société Internationale pour l’Étude de la Philosophie Médiévale, 25. bis 30. August 1997 in Erfurt, edited by Jan A. Aertsen and Andreas Speer. Berlin: Walter de Gruyter, 1998.

———. Oxford Physics in the Thirteenth Century (ca. 1250 – 1270): Motion, Infinity, Place and Time. Leiden: Brill, 2000. First major discussion of Rufus’s influence the tradition of natural philosophy.

Weisberg, Michael, and Rega Wood. “Richard Rufus’s Theory of Mixture: A Medieval Explanation of Chemical Combination.” In Chemical Explanation: Characteristics, Development, Autonomy, ed. Joseph E. Earley, Sr. New York: New York Academy of Sciences, 2003.

Wood, Rega. “Richard Rufus of Cornwall and Aristotle’s Physics.” Franciscan Studies 52 (1992): 247–81. Announces the rediscovery of In Phys.

———. “Richard Rufus of Cornwall on Creation: The Reception of Aristotelian Physics in the West.” Medieval Philosophy and Theology 2 (1992): 1–30. Describes the evolution of Rufus’s views on the beginning of time. Discusses Rufus’s version of the argument Kant presents in his “First Antinomy of Pure Reason.”

———. “Richard Rufus: Physics at Paris Before 1240.” Documenti e studi sulla tradizione filosofica medievale 5 (1994): 87–127. Describes Rufus’s views on the place of the world.

———. “Richard Rufus’ ‘Speculum animae.’ Epistemology and the Introduction of Aristotle in the West.” In Die Bibliotheca Amploniana. Ihre Bedeutung im Spannungsfeld von Aristotelismus, Nominalismus und Humanismus, edited by Andreas Speer. Miscellanea mediaevalia 23. Berlin: De Gruyter, 1995. First study of Rufus’s epistemology. Describes a new manuscript and a new title for a work on perception, previously described as part of a theological work on the miserable human condition, Miserabilia humana condicio.

———. “Roger Bacon: Richard Rufus’ Successor as a Parisian Physics Professor.” Vivarium 35 (1997): 222–250. Compares Bacon and Rufus.

———. “Richard Rufus’s De anima Commentary: The Earliest Known, Surviving, Western De anima Commentary.” Medieval Philosophy and Theology 10 (2001): 119–156.

———. “Richard Rufus of Cornwall.” In A Companion to Philosophy in the Middle Ages, edited by Jorge J. E. Gracia and Timothy B. Noone. Oxford: Blackwell Publishing, 2003.

———. “Richard Rufus of Cornwall’s Significance in the Western Scientific Tradition.” In Albertus Magnus und die Anfänge der Aristoteles-Rezeption im lateinischen Mittelalter: Von Richardus Rufus bis zu Franciscus de Mayronis, edited by Ludger Honnefelder, Rega Wood, Mechthild Dreyer, et al. Münster: Aschendorff Verlag, 2005. Compares the reception of Rufus’s views on the beginning of the world, the place of the world, and projectile motion.

———, and Michael Weisberg. “Interpreting Aristotle on Mixture: Problems about Elemental Composition from Philoponus to Cooper.” Studies in History and Philosophy of Science 35 (2004): 681–706. Compares Rufus with other interpreters of Aristotle on mixture.

———, and Jennifer Ottmanr. “Richard Rufus of Cornwall.” In Medieval Science, Technology, and Medicine, edited by Thomas Glock, Steven J. Livesey, and Faith Wallis. New York: Routledge, 2005.

Rega Wood