DES CARTES,

THE space which we can devote to this biography would be utterly insufficient to give the smallest account of the varied philosophical labours of its subject; still less to recount their consequences. We shall therefore confine ourselves almost entirely to his personal life; the more so, as the private history of Des Cartes is not so well known to the world in general, as is the history of the mathematician, the optician, the natural philosopher, the metaphysician, the anatomist, the musician, etc., to those who study these several sciences.

René Des Cartes* du Perron (the latter name being derived from a lordship inherited from his mother, by which he was distinguished from his elder brother) was born at La Haye, in Touraine, March 31, 1596. From his mother, who died shortly after, he inherited a feeble constitution. His father, Joachim Des Cartes, had served in the civil wars, and was of a noble family, "of which," says Baillet, neither origin could be traced, nor mésalliance while it lasted."

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His early inclination for study induced his father to send him to the College of La Flèche when he was only eight years old. We have the accounts of extraordinary progress which are usually related of men after they have become distinguished; but what is not so common, we find that he was allowed to keep his bed in the morning as long as he pleased, partly from the weakness of his health, and partly because he was observed to be of a meditative turn. We mention this, because it afterwards became his usual habit to study in bed; and certainly some parts of his philosophy bear the marks of it.

He left La Flèche in eight years and a half, with great reputation, and a disgust for all books and methods then in use. He was sent to Paris at the age of seventeen, under the care of a servant, and fell into the fashionable vice of gambling; but at the same time he cultivated the acquaintance of Mydorget and Mersenne. He finally became disgusted with his favourite pursuit, hired a solitary house in the Fauxbourg St. Germain, and resumed his studies.

At the age of twenty-one, he enlisted as a volunteer under the Prince of Orange. At Breda, the solution of a problem introduced him to Beekman. Here he wrote his "Treatise on Music," of which the latter (to whom it had been entrusted) gave himself

The life of Des Cartes has been written with great minuteness by M. Baillet, author of the Jugemens des Savans," &c., in two vols. 4to, Paris, 1690; abridged, Paris, 1693; translated into English the same year. This appears to have been the source from which all accounts have been

derived.

To explain in the briefest terms who these and other friends of Des Cartes were, would make us exceed the prescribed bounds. Our reader must be content to be referred to a biographical dictionary for these and others not known, except to mathematicians.

out as the author. In 1619, he enlisted as a volunteer under the Duke of Bavaria ; and while thus engaged, he tells us he laid the foundations of his philosophy (November 10); after three wonderful dreams. Quitting the service he was engaged in, after having been present at the siege of Prague, he travelled till the end of 1619. He then returned to Paris, where it was believed he was a Rosicrucian, and his continual presence in public was necessary to repel the suspicion. At this time he appears to have laid the foundation of his mathematical methods. After travelling into Italy, he settled again at Paris, and we now find him in habits of friendship with Beaune (afterwards his commentator), Morin, Frenicle, and others, and occupying himself with practical optics. In 1628, he served at the siege of Rochelle.

To avoid society, in 1629, he migrated to Holland, where he passed twenty years. He removed from town to town, hiding his actual residence from all but one or two friends. He occupied himself at first with his optics, and with the considerations which led him, in a few years, to publish his Treatise on Meteors," as also with chemistry and anatomy. We now find him in communication with Reneri and Gassendi. He made a short voyage to England, of which nothing is recorded, except some magnetic observations made near London. About 1633, his philosophical opinions were first taught by Reneri, at Deventer. His "Treatise on the World," written about this time, was suppressed by him when he heard what had happened to Galileo in Italy; and except some meteorological observations, we find nothing to notice till 1637, when he published his "Principles of Philosophy," in which the well-known hypothesis of vortices is propounded, together with his dioptrical and meteorological theories. This publication was immediately combated in different parts by Roberval, Fromondus, Plempius, Fermat, the elder Pascal, and others. Without going into these and other now uninteresting disputes, it is only necessary to state, that Fermat, Pascal, Roberval, and several others, were soon after in friendly communication with Des Cartes. After the famous problem of the Cycloid, which was propounded about this time (1638-39), Des Cartes, as he had several times done before, renounced geometry; and his work bearing that title (but which is, in fact, his celebrated application of algebra to geometry) was not published by himself, but by his friend De Beaune, who wrote a comment on it at his desire.

In the mean time, his philosophy was fast rising into repute in Holland, where, in 1639, a public panegyric was made upon it at Utrecht, on the death of Reneri. We pass over the various disputes upon it, both at Utrecht and Paris. In 1640, Des Cartes was nearly induced to take up his residence in England, under the protection of Charles I.: but the domestic troubles, which within two years broke out into civil war, interfered with the completion of this arrangement. His father died at the end of the same year; in which he also lost a child named Francina, whom he owned as his daughter, but concerning whose parentage, whether it were legitimate or not, nothing certain is known. Des Cartes was attacked at this time by the Jesuits in France, and by a party in Holland, which asserted that he himself was a Jesuit. The hostility of his Dutch opponents did not materially retard the progress of his opinions, nor could the Jesuits prevent his receiving a flattering invitation from Louis XIII. to return to France.

In 1641 appeared his "Meditations de Primâ Philosophia, on the Soul, on Freewill, and on the Existence of a Creator." Various parts of this treatise were criticised by Hobbes, Gassendi, and some others; but so much was the reputation of Des Cartes increased in France, that the exertions of Mersenne, made by the desire of the author, could not obtain more than one opponent to this work out of all the Sorbonne. This was the afterwards celebrated Arnaud, between whom and Des Cartes a friendly controversy was maintained. But in Holland, the active enmity of Voet, the rector of the university