(b. Ferrara, Italy, 26 February 1586;
d. Genoa, 30 June 1650), natural philosophy, magnetism, mechanics, methodology. For the original article on Cabeo see DSB, vol. 3.
Cabeo, a Catholic priest who had entered the Jesuit religious order as a novice in 1602, is best known for his two major publications, Philosophia magnetica (Magnetic philosophy, 1629) and In quatuor libros meteorologicorum Aristotelis commentaria (Commentary in four books on Aristotle’s Meteorology, 1646). The first of these works addresses the phenomenon of magnetism, especially as discussed by the Englishman William Gilbert in his famous De magnete (On the magnet, 1600), while the second is a lengthy commentary on one of Aristotle’s physical works, a form that allowed Cabeo to discuss a very broad range of topics not restricted to meteorology itself but encompassing many aspects of Aristotle’s so-called sub-lunary (below the moon) region of the universe. Despite his many disagreements with Aristotle, Cabeo shared with the latter the conviction that the Earth is stationary at the center of the universe.
Career . Cabeo’s academic training occurred primarily at Parma, following the usual Jesuit curriculum of the period, and included the study of logic, natural philosophy (centered on the works of Aristotle), metaphysics, and theology; he clearly also studied some mathematics. Following the completion of his studies around 1616, Cabeo taught theology, philosophy, and metaphysics at Parma until 1621; he subsequently spent several years living at the Jesuit college back in Ferrara, his birthplace, and taught some theology there in the late 1620s. At the end of his life he returned to teaching, now at the Jesuit college in Genoa. In the meanwhile, he served the ducal courts in Mantua and in Modena, made use of his mathematical expertise in work on civil engineering projects, and was an itinerant preacher. He remained throughout his life engaged in issues of mathematics and natural philosophy, debating issues of mechanics, free fall, and motion with such contemporaries and familiars as Giovanni Battista Baliani, Benedetto Castelli, and Giovanni Battista Riccioli, as well as publishing his two major treatises. His interests covered a wide range of contemporary natural philosophy, however, beyond those questions of motion associated with his older contemporary Galileo.
Magnetism and Electricity . His first book, the Philosophia magnetica, discussed not only Gilbert’s but also Cabeo’s own experimental investigations of terrestrial magnetism as well as magnetized iron and “lodestone” (the mineral magnetite). The central focus of his work, like Gilbert’s before him, was therefore the study of the magnetic behaviors of compass needles. Where Gilbert, however, argued that the Earth itself is a giant magnet, whose poles reproduce the poles of an ordinary magnet and with which it interacts, Cabeo maintained instead that magnetic properties are inherent to certain sorts of matter; they did not subsist in their relationships to the great magnet, the Earth. Indeed, Cabeo denied that the Earth itself is a great magnet, even though it contains matter lending it magnetic effects. He also, again following Gilbert, discussed magnetic attraction between rubbed objects (typically, pieces of amber resin) and light objects such as bits of straw or paper; the attractive virtues of such electrified bodies appeared to be sufficiently similar to those of magnets that it seemed appropriate to investigate them together. In accounting for the production of electrical attraction by certain kinds of matter when they are rubbed, Cabeo—always, as a natural philosopher, on the lookout for causal explanations of phenomena, not simply their descriptions—suggested that the rubbing stimulates the emission of tiny particles, as an effluvium, from the rubbed body’s pores, which, in its interaction with the surrounding air, tends to move light objects toward it as a result of the rarified air’s subsequent behavior.
In the Philosophia magnetica, Cabeo considered the methodological and epistemological issues relating to his experimental investigations. He stressed that his work sought the causes behind natural effects (this being the usual goal of Aristotelian-style natural philosophy) but that he would proceed by borrowing the approach of the mathematicians because it was so clear and demonstrative. He also stressed the extent to which his discussions were based upon experimental work, his experiments having been repeated numerous times, with multiple witnesses on hand to guarantee the truth of his reports. The necessity of saying such things stemmed from the unusual nature of the phenomena Cabeo described; neither magnetic nor electrical effects were generally familiar from everyday experience, and arguments based on unusual and contrived experimental behaviors therefore needed special justification to be accepted.
Experimental Philosophy . Cabeo’s use of experimental procedures in natural philosophy is also a prominent feature of his other major publication, the 1646 commentary on Aristotle’s Meteorology. Indeed, when the work came to be reprinted (Rome, 1686), it was given a slightly revised title: Preceding the old title that described the work as comprising a commentary on Aristotle, the new edition advertised itself as Philosophia experimentalis, or experimental philosophy. One of Cabeo’s topics concerned the behavior of falling bodies, which Galileo had made famous in his Discorsi of 1638. Cabeo affirmed Galileo’s claim that all bodies—at least those made of the same material—tend to fall at the same rate as one another, rather than the heavier ones falling faster (the Aristotelian view). Cabeo justified his claims using reports of repeated and witnessed experimental trials. Another Galilean assertion, which Galileo had attempted to demonstrate mathematically as derivable from the simpler components principles of (roughly) horizontal inertia and vertical, uniformly accelerated fall, Cabeo characteristically attempted to test by direct trial, regarding Galileo’s assertion as based too much on speculative reasoning. In his commentary Cabeo described a succession of paper panels arranged along the presumed path of a cannonball, the cannon being fired through them so as to punch a hole in each panel. The holes thus traced out the curving path of the cannonball. Cabeo said, as usual, that he had tried this many times, and with additional observers; he had also examined the curving path of a jet of water.
The full scope of Cabeo’s commentary on Aristotle’s Meteorology thus presented a full-scale example of a new style of natural philosophy, an experimental philosophy that made free use of mathematical tools. This new style was also developed by many of Cabeo’s fellow Jesuits in the same period. It should not be imagined, however, that all Cabeo’s work appears “modern”; besides the material already discussed, his commentary also discussed chemical and alchemical questions as well as expressing belief in the occult effects of the heavens upon the Earth, among a vast miscellany of other topics. Not only did he reject the motion of the Earth, which for him remained central in the universe, but he also denied the possibility of a vacuum in nature. Both of these debated positions were common among Jesuit natural philosophers of his time.
WORKS BY CABEO
Philosophia magnetica. Ferrara, Italy: F. Suzzi, 1629; Cologne, Germany: I. Kinckium, 1629. Note that different copies cite one or the other place of publication.
In quatuor libros meteorologicorum Aristotelis commentaria. Rome: Francisco Corbelletto, 1646.
Baldini, Ugo. Legem impone subactis: Studi su filosofia e scienza dei Gesuiti in Italia 1540–1632. Rome: Bulzoni, 1992. The appendix to chapter 11 is particularly informative as to Cabeo’s presence at various Jesuit colleges.
Costantini, Claudio. Baliani e i Gesuiti: Annotazioni in margine alla corrispondenza del Baliani con Gio. Luigi Confalonieri e Orazio Grassi. Florence: Giunti Barbera, 1969. Contains material on Cabeo’s relations with Baliani.
Dear, Peter. Discipline and Experience: The Mathematical Way in the Scientific Revolution. Chicago: University of Chicago Press, 1995.
Heilbron, John L. Electricity in the 17th and 18th Centuries: A Study of Early Modern Physics. Berkeley: University of California Press; reprint, Mineola, NY: Dover, 1999.
Ingegno, Alfonso. “Cabeo, Niccolò.” In Dizionario Biografico degli Italiani. Vol. 15. Rome: Istituto della Enciclopedia Italiana, 1972. An excellent general treatment.
Maffioli, Cesare S. Out of Galileo: The Science of Waters 1628–1718. Rotterdam: Erasmus, 1994. Discusses Cabeo in relation to Castelli and Baliani on the practical hydraulics of canals and rivers.
Moscovici, Serge. L’Expérience du mouvement: Jean-Baptiste Baliani disciple et critique de Galilée. Paris: Hermann, 1967.
Pumfrey, Stephen. “Neo-Aristotelianism and the Magnetic Philosophy.” In New Perspectives on Renaissance Thought: Essays in the History of Science, Education, and Philosophy inMemory of Charles B. Schmitt, edited by John Henry and Sarah Hutton. London: Duckworth, 1990.
Sommervogel, Carlos, et al., eds. Bibliothèque de la Compagnie de Jésus. 12 vols. Louvain: Éditions de la Bibliothéque S.J., 1960. See vol. 2.
(b. Ferrara, Italy, 26 February 1586; d. Genoa, Italy, 30 June 1650),
meteorology, magnetism, mathematics.
A Jesuit, Cabeo taught moral theology and mathematics in Parma, then was a preacher in various Italian cities until he settled in Genoa, where he taught mathematics. He published two major works, Philosophia magnetica and In quatuor libros meteorologicorum Aristotelis commentaria.
Cabeo is remembered mainly because in Genoa he became acquainted with Giovanni Battista Baliani, who at the fortress of Savona had experimented with falling weights, which, although of different heaviness, took almost the same length of time to reach the ground. Cabeo interpreted these experiments perhaps too broadly and was therefore the indirect cause ofother experiments conducted by Vincenzo Renieri, who refers to them in a letter of 13 March 1641 to Galileo. These experiments, however, showed considerable differences in time of descent because of air resistance. Renieri wrote that he had undertaken them “because a certain Jesuit writes that [two different weights] fall in the same length of time.” Galileo wrote in the Discorsi e dimostrazioni matematiche intorno a due nuove scienze (Edizione Nazionale delle Opere, VIII, 128) that to conduct such experiments “Involves some difficulties” and referred to descent along an inclined plane and to the oscillations of a pendulum. Thus Vincenzo Viviani’s account of the results of Galileo’s experiments that involved dropping different weights from the top of the bell tower in Pisa seems to be completely unfounded.
I. Original Works. Cabeo’s books are Philosophia magnetica in qua magnetis natura penitus explicatur, et omnium quae hoc lapide cernuntur, causae propriae afferuntur… (Ferrara, 1629); and In quatuor libros meteorologicorum Aristotelis commeniaria…(Rome, 1646).
II. Secondary Literature. Galileo Galilei, Discorsi e dimostrazioni matematiche intorno a due nuove scienze, Adriano Carugo and Ludovico Geymonat, eds. (Turin, 1958), p. 689, note; and see Carlos Sommervogel, Bibliothèque de la Compagnie de Jésus, II, pt. 1 (Brussels-Paris, 1891).