Giovanni Alfonso Borelli

1608-1679

Italian Naturalist, Mathemetician and Physicist

Giovanni Borelli was born in Naples, Italy. Little is known about his early life, education, and family, other than his precocious mastery of mathematics. There is uncertainty about whether he ever studied medicine formally, but he did study mathematics with Benedetto Castelli (1577-1644) in Rome. Borelli was appointed to the chair of mathematics at the University of Messina by 1640. In 1642, inspired by the work of Galileo Galilei (1564-1642), Borelli obtained the consent of the University to take a prolonged leave from his professorship in order to study with Galileo and Evangelista Torricelli (1608-1647) in Florence. Unfortunately, Galileo died that year and Borelli returned to the University. In 1656 Ferdinand, Duke of Tuscany invited Borelli to serve as professor of mathematics at the University of Pisa. During the same year, Marcello Malpighi (1628-1694) joined the university as a professor of theoretical medicine. Malpighi held doctorates in both medicine and philosophy and was the founder of microscopic anatomy. Borelli and Malpighi became good friends and leaders of the Accademia del Cimento (Academy of Experiments), which was founded in Florence in 1657.

The Accademia del Cimento, one of the first scientific societies, helped establish Pisa as a center of research in mathematics and the natural sciences. After 12 years at Pisa, and many quarrels with his colleagues, Borelli left the university to seek quieter and healthier surroundings. In 1667 Borelli returned to the University of Messina, where he became involved in literary and antiquarian studies, investigated an eruption of Mount Etna, and continued to work on the problem of animal motion. In 1674 he was accused of being involved in a conspiracy to free Sicily from Spain. Forced into exile, he fled to Rome, where he lived under the protection of Christina, former queen of Sweden. Borelli died before his great work De motu animalium (On Motion in Animals, 1680-81) was published. An introduction was added by a church official who commended Borelli for upholding the authority of the Church in his lectures on astronomy. In physiological matters, too, Borelli remained a faithful son of the Church by acknowledging that, although he had attempted to explain the movements of the body in terms of purely mechanical principles, all the mechanical phenomena described in his book were ultimately governed by the soul.

The seventeenth century was a time of great ferment and change in scientific and medical thought. The Scientific Revolution created skepticism about ancient medical theories and resulted in the search for a simple system that could guide medical practice. René Descartes's (1596-1650) concept of the human body as a machine that functions in accordance with mechanical principles was very influential in medical thought. Physicians and scientists who accepted the mechanical model of physiology were called iatrophysicists. Those who thought of life as a series of chemical processes were called iatrochemists. Whereas Descartes was the founder of iatromechanism as a philosophy, Borelli was the founder of iatrophysics as an experimental science. Borelli was especially interested in the problem of muscle action.

De motu animalium was a sustained analysis of the mechanics of muscle contraction that dealt with the movements of individual muscles and groups of muscles treated geometrically in terms of mechanical principles. Animal movements were divided into external movements, such as those carried out by the skeletal muscles, and internal movements, such as those of the heart and viscera. Borelli's method of study involved a progression from the simplest element of the motor system, the independent muscles, up to the more complicated organs and organ systems, and finally the power of movement of the organism considered as a whole. According to Borelli, the fleshy muscular fibers played a fundamental role in muscle contraction; the fibers of the tendons, in contrast, were merely passive agents, which did not take part in contraction. The action of the heart particularly intrigued Borelli. Unlike Descartes, he recognized that the heart was a muscular pump rather than a heat engine and confirmed this by simple experiments.

Although Borelli is primarily remembered for his attempts to explain muscular movement and other body functions according to the laws of statics and dynamics, he was also one of the early microscopists. Borelli carried out microscopic investigations of the circulation of the blood, nematodes, textile fibers, and spider eggs. Borelli also wrote many astronomical works, including a treatise in 1666 that considered the influence of attraction on the satellites of Jupiter. In a letter published in 1665 under the pseudonym Pier Maria Mutoli, he was the first to suggest the idea that comets travel in a parabolic path.

LOIS N. MAGNER