GASSENDI, PIERRE French philosopher, scientist and mathematician, was born of poor parents at Champ tercier, in Provence, on Jan. 22, 1592. He studied at Digne and at the University of Aix, returning to Digne as a lecturer in theology in 1612. Five years later he took holy orders, and was called to the chair of philosophy at Aix.
After 1628 Gassendi travelled in Flanders and Holland. Dur ing this time he wrote, at the instance of Mersenne, his examina tion of the mystical philosophy of Robert Fludd (Epistolica dis sertatio in qua praecipua principia philosophiae Ro. Fluddi de teguntur, 1631), an essay on parhelia (Epistola de parheliis), and some valuable observations on the transit of Mercury which had been foretold by Kepler. He returned to France in 1631, and two years later became provost of the cathedral church at Digne. Some years were then spent in travelling through Provence with the duke of Angouleme, governor of the department. The only literary work of this period is the Life of Peiresc. In 1642 he was engaged by Mersenne in controversy with Descartes. His objections to the fundamental propositions of Descartes were published in 1642 ; they appear as the fifth in the series contained in the works of Descartes. In these objections Gassendi's tend ency towards the empirical school of speculation appears more pronounced than in any of his other writings. In 1645 he accepted the chair of mathematics in the College Royal at Paris, and lec tured for many years with great success. In addition to con troversial writings on physical questions, there appeared during this period the first of the works by which he is known in the history of philosophy. In 1647 he published the treatise De vita, moribus, et doctrina Epicuri libri octo. The work was well re ceived, and two years later appeared his commentary on the tenth book of Diogenes Laertius, De vita, moribus, et placitis Epicuri, seu Animadversiones in X. librum Diog. Laer. (Lyons, 1649 ; last edition, 1675). In the same year the more important Syntagma philosopliiae Epicuri (Lyons, 1649; Amsterdam, 1684) was pub lished. Gassendi died at Paris on Oct. 24. Like Bacon, Gassendi urged the importance of experimental research, but he added little to our knowledge of physical science. In philosophy he opposed the blind acceptance of Aristotle, re vived atomism and advocated an empirical realism. But he was not a consistent empiricist, for while he constantly maintains "that there is nothing in the intellect which has not been in the senses," and that the imaginative faculty is the counterpart of sense, he at the same time admits that the intellect, which he affirms to be immaterial and immortal, attains notions and truths of which sensation or imagination can give us not the slightest apprehension. (Op. ii. 383.) He instances the capacity of form ing "general notions" and universals, the notion of God and the power of reflection.
The first part of the Syntagma philosophicum, which exhibits Gassendi's critical ability, his wide reading, and also his deficiency in speculative power, contains at least one praiseworthy portion, a sketch of the history of the science. It also contends that the true method of research is the analytic, rising from lower to higher notions, though it admits that inductive reasoning, as conceived by Bacon, rests on a general proposition not itself proved by induction. In the second part of the Syntagma, the physics, he approves of the Epicurean physics, but rejects the Epicurean negation of God and particular providence, and of an immaterial rational soul, endowed with immortality, capable of free de termination, and specially created. The hypothesis of the calor vitalis (vital heat), a species of anima mundi (world-soul), which is introduced as physical explanation of physical phenomena, does not seem to throw much light on the special problems which it is invoked to solve. Nor is his theory of the weight essential to atoms as being due to an inner force impelling them to motion in any way reconcilable with his general doctrine of mechanical causes. In the third part, the ethics, there is little beyond a milder statement of the Epicurean moral code, and a mass of historical quotations. The final end of life is happiness, and happiness is harmony of soul and body (tranquillitas animi et indolentia cor poris) .
BIBLIOGRAPHY.—Gassendi's collected works, including his correBibliography.—Gassendi's collected works, including his corre- spondence and a life by Sorbiere, were published by Montmort, 6 vols. (Lyons, 1658). An untrustworthy abridgment of his philosophy was given by his friend, the celebrated traveller, Bernier, Abrege de la phitosophie de Gassendi, 8 vols. (1678) . See also Bougerel, Vie de Gassendi (1737) ; Damiron, Memoire sur Gassendi, and Memoires pour servir a l'histoire de philosophie au XVIle siecle (1858) ; G. S. Brett, Philosophy of Gassendi (1908) ; P. F. Thomas, La Philosophie de Gassendi (1889) ; Ritter, Geschichte der Philosophie, x.; Feuerbach, Gesch. d. neu. Phil. von Bacon bis Spinoza, 127-15o; F. X. Kiefl, P. Gassendis Erkenntnistheorie and seine Stellung zum Materialismus (1893) ; and Delambre, Hist. de l'Astronomie, vol. ii. (1821), for his astronomical contributions.