Grosseteste, Robert (c. 1168–1253)

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(c. 11681253)

Robert Grosseteste was one of the most influential Englishmen of his dayinitiator of the English scientific tradition, one of the first chancellors of Oxford University, a famous teacher and commentator on the newly discovered works of Aristotle, an important translator from the Greek, friend to the mendicant orders, first lecturer to the Oxford Franciscans, and zealous bishop of England's largest diocese. However, his life is imperfectly known and much of his work remains unpublished. He was born of humble parents in the county of Suffolk between 1168 and 1175 and by 1190 had become magister in artibus at either Oxford or Paris. Sometime between 1190 and 1198 he was a member of the household of William de Vere, bishop of Hereford, and may have taught in the Hereford schools. After the bishop's death in 1198, Grosseteste was a member of the arts faculty at Oxford or possibly at Cambridge. He probably studied theology at Paris during the suspendium clericorum, 12091214. At some time between 1214 and 1221 he became chancellor of Oxford University. In 1229 he became the first lecturer to the Oxford Franciscans, leaving this post only on his elevation to the see of Lincoln in 1235. He was bishop of Lincoln until his death eighteen years later.

Grosseteste lived at a crucial period in intellectual history: The scientific and philosophical writings of the Muslims were just becoming known in Latin Europe and the works of the Hellenistic writers and the recently rediscovered works of Aristotle were being translated, disseminated, and lectured upon. As teacher, commentator, and translator, he took an active part in this movement. Basically Augustinian in outlook and relying heavily on the standard authors, he was nevertheless deeply influenced by Muslim learning, especially Avicenna and the astronomers, by the Jew Solomon ben Judah ibn Gabirol (Avicebrón), and by the newly found Aristotelian works. He never wrote a comprehensive philosophical work or devised a system, but he developed many characteristic views that have had a profound influence on the later development of both philosophy and science. The most important of his many philosophical works are De Luce (Light), De Motu Corporali et Luce (Corporal Motion and Light), Hexameron, and commentaries on Aristotle's Posterior Analytics and Physics.

Light Metaphysics

Basic to Grosseteste's view of the universe is his metaphysics of light. He held that in the beginning God created the first corporeal form (lux ), which had the property of instantaneously multiplying itself infinitely in every direction, and simple matter, an unextended substance. The original point of light was joined to unextended matter (since matter and form never exist separately) and in its expansion drew matter out into spatial dimensions. The resulting universe was a sphere extremely rare at the periphery but dense and opaque near the center. It was finite because a simple substance multiplied an infinite number of times would result in a finite quantity, and the matter of the periphery (the firmament) was completely actualized and capable of no further change.

When this perfect first body, containing only first matter and first form, had been created, it diffused its reflected light (lumen ) back to the center, where the lumen gathered together the mass existing below the first body, again rarefying the outermost parts and making the center more dense. The second sphere was thus formed, as were, by a similar process, all thirteen spheres, including the four elements. On the outside of our universe, matter is completely actualized and capable of no further change, while at the center the degree of actualization is less and matter remains susceptible of taking on a variety of forms. From first form (light) every subsequent form is generated, both substantial and accidental, and every privation derives from the privation of light.

Since all things have in common first form and first matter, they are, in a sense, one. But each thing includes a hierarchy of form superadded to the original form of corporeity, making it the individual thing it is. Most of Grosseteste's other views were either derived from or imply his light metaphysics. He considered light the cause of local motion, the means by which the soul operates on the body (he denied that the soul is the form or perfection of the body), and the principle of intelligibility in the created universe.

Theories of Knowledge

Grosseteste had two distinct theories of knowledge. The first, in the Augustinian tradition and strongly influenced by Avicenna, held that men may acquire knowledge by virtue of the intellect alone, without recourse to sense. The second held that certain knowledge may also be gained through sense perception. Although sense turns toward matter and is therefore unstable, imperfect, and subject to imaginative embellishments, it also follows reason, even though confusedly, and does not obscure the species it provides. Reason, which understands the principles of nature in a single manner, either corrects or completes whatever was lacking in the senses.

Both these ways of knowing involve another of Grosseteste's key concepts, the purgation of the mind. It is not until the desires of one's mind (affectus mentis ) are purged of error that the gaze of one's mind (aspectus mentis ) can be raised to the eternal and true and can overcome the delusions caused by corporeal phantasms. "Many men," Grosseteste said, "can prove by sure reasons that the Intelligences exist and that God exists but they do not understand the Divine Essence or the non-corporeity of the Intelligences. Aristotle and others, who firmly knew by discursive reasoning that eternity was simple but saw it under the phantasms of temporal extension, have affirmed many improper things such as the perpetuity of time and motion and consequently the eternity of the world." In this quotation from the Commentary on the Physics, we see Grosseteste at once as one of the foremost critics of the dangers latent in the works of Aristotle and yet also among the leaders in introducing Aristotle's natural philosophy into western Europe.


One of Grosseteste's most original and influential teachings concerns infinite aggregates. He believed that "one infinite number can be related in any proportion, numeral or non-numeral, to another infinite number." To God, infinite numbers are finite, and he determines the primary cubit (and every other measure) by a certain infinite number and a half-cubit by another infinite number half (to him) that of the cubit, and so on. But such a manner of measuring is possible only to one to whom the infinite is finite. Being finite, we must necessarily adopt a different manner of measuring, that is, by commensurable magnitudes as accidents of matter.

Scientific Method

It is as a scientist and innovator in scientific method, however, that Grosseteste attracted the interest of the twentieth century. In his most important scientific writings he progressively developed a characteristic method of investigating nature that employed analysis (resolutio ) and synthesis (compositio ) in physical inquiries, first breaking down a problem into its simplest parts, then framing a hypothesis that would show how these elements are to be combined in order to produce the phenomenon under investigation. He also held that an experimental universal of provisional truth might be obtained by observing that a given effect always results from a particular cause, if one controlled his observation by eliminating any other possible cause of the effect.

In addition to this framework, Grosseteste used experiments as an integral part of his investigation: as aids in accomplishing his analysis, as suggestions in framing his explanatory hypothesis, and most important, as tests of the truth or falsity of a hypothesis. He also employed mathematics in his researches, holding that since light is the cause of local motion and the means by which superior bodies act on inferior ones, and that since light behaves according to geometric rules, therefore all local motion can be described mathematically. He denied, however, that mathematical entities have any objective being and insisted that they are simply abstractions from physical bodies and exist only in the minds of mathematicians.

Another of his basic principles was that of the subordination of sciences. A superior science, he said, may provide the cause for which the inferior science provides the effect. In the study of heavenly bodies, for instance, the sciences of mathematics, astronomy, and physics are concerned. Mathematicians abstract magnitudes from motion and matter and demonstrate the accidents per se with respect to magnitudes. Physicists, on the other hand, demonstrate the figured magnitudes in the sense that they belong to physical bodies. Astronomers have much in common with physicists, but whereas they might both be studying the same bodyfor instance, the moonthe physicist demonstrates that the predicate belongs to the subject by nature, while the astronomer does not care whether it belongs to it by nature or not.

Grosseteste wrote four works on astronomy. His work De Sphaera (On the Sphere) is a theoretical treatise. The other three works are primarily concerned with reforming the Julian calendar, which was nearly four days in error at that time. Using the works of Ptolemy, al-Battani, and Ibn Thebit, he worked out a program for calendar reform that continued to find supporters until it was largely incorporated into the Gregorian reform of 1582.

Grosseteste was in many ways the hinge between the early and late Middle Ages. He had at his disposal the standard late Roman authors and the recently introduced Greek and Arabic sources. His powerful, resourceful, and disciplined mind assimilated and transformed this material. He left many loose ends and sometimes failed to think through his positions; and in his scientific works, despite his methodological triumphs, he was not a notable experimenter. Still, so powerful was his thought that he influenced an uninterrupted succession of philosophers and scientists throughout Europe for 300 years after his death.

See also Aristotle; Augustinianism; Avicenna; Ibn Gabirol, Solomon ben Judah; Scientific Method; Sensa.



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Bibliography updated by Neil T. Lewis (2005)

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Grosseteste, Robert (c. 1168–1253)

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