The Cartesian philosophy was first taught in the schools of Deventer, 1633 : it attracted many zealous admirers, and excited against him a host of opponents. The system of Des Cartes obtained so much credit in Great Britain, that the inventor was invited to settle in England, as well by the king as by some of the principal nobility. This invitation lie would probably have accepted, had not the civil wars prevented Charles I. from being able to render the philosopher all the patronage which lie had formerly tendered him. At this period he was forced into many disputes, in the course of which, as well.as by his collateral eon duct, he displayed an eager desire to be considered the father of a sect, and disco vers more jealousy and ambition than Le came a philosopher.
During Des Cartes's residence in Hol land, he went occasionally to his native country, where, in 1643, he published an abstract of his philosophy, underthe title of" Philosophical Specimens." He was promised, on one of these visits, an annual pension of 3000 livres, which he never re ceived., He was now invited by Christina, Queen of Sweden, to visit Stockholm. That learned princess had read with de light his treatise " On the Passions," and was earnestly desirous to be instructed by him in the principles of philosophy. Des Canes arrived at Stockholm in 1649, where he received a most friendly and respectfulreception from the enlightened queen, who urged him to settle in her kingdom, and assist her in establishing an academy of sciences. He had, how ever,been scarcely four months in that severe climate, when, in his visits to the sovereign, whom he instructed in the principles of philosophy, he• caught a cold, which brought on an inflammation in his lungs, that put a period to his life, in 1650. His remains were interred ht the cemetery for foreigners, and a long eulogium inscribed on his tomb : but in 1666 his bones were transported to France, and placed, with all the circum stances of pomp, in the church of St. Genevieve. Such was the life of this great man : his writings and system require a, more detailed account.
On the subject of logic, he says, no thing is ever to be admitted as true,which is not certainly and evidently known to be so, and which cannot be possibly doubted. In proving any truth, the ideas are always to be brought forward in a certain order, beginning from things the most simple, and advancing by regular steps to those which are more complex and difficult. With regard to metaphy sics, Des Cartes says, that since man is under the influence of prejudice, he ought, once in his life, to doubt of every thing ; even whether sensible objects have a real existence ; and also of the truth of mathematical axioms. The first
principle of the Cartesian philosophy is this, " 1 THINK, THEREFORE I AM :" this is the foundation of Des Cartes's physics : that on which his physics is built is, THAT NOTHING EXISTS BUT SUBSTANCES." Substance he makes of two kinds ; the one that thinks, the other is extended: so that actual thought and actual extension make the essence of substance. The essence of matterbeing thus fixed in extension, Des Cartes con cludes that there is no vacuum, nor any possibility of it in nature, but that the universe is absolutely full : by this princi ple mere space is quite excluded ; for extension being implied in the idea of space, matter is so too.
Des Cartes defines motion to be the translation of a body from the neighbour hood of others that are in contact with it, and considered as at rest, to the neigh bourhood of other bodies ; by which he destroys the distinction between motion that is absolute or real, and that which is relative or apparent. He maintains,th at the same quantity of motion is always preserved in the universe, because God must be supposed to act in the most constant and immutable manner : and hence also he deduces his three laws of motion.
Upon these principles Des Cartes ex plains mechanically how the world was formed, and how the present phenomena of nature came to arise. He supposes that God created matter of an indefinite extension, which he separated into small square portions or masses, full of angles ; that he impressed two motions on this matter ; the one, by which each part re volved about its own centre; and another, by which an assemblage or system of them turned round a common centre. From whence arose as many different vor tices, or eddies, as there were different masses of matter thus moving about com mon centres.
The consequence of these motions in each vortex, according to Des Cartes, is as follows : the parts of matter could not thus move and revolve amongst one ano ther, without having theirangles gradual ly broken : and this continual friction of parts and angles must produce three ele ments : the first of these, an infinitely fine dust formed of the angles broken off; the second, the spheres remaining, after all the angular parts are thus removed; and those particles not yet rendered smooth and spherical, but still retaining some of their angles, and hainous parts, form the third element.