A second principle is, the inevitable ascent of our thought from the fragmentary to the perfect, from the finite to the infinite. Thus the thought of the infinite is an "innate idea," a part of man's potential consciousness. This principle (set forth in one of the selections given herewith) is the Cartesian form of the a priori argument for the Divine existence, which like other a priori forms is viewed by critics not as a proof in pure logic, but as a commanding and luminous appeal to man's entire moral and intellectual nature.
A third principle is, that the material universe is necessarily reduced in our thought ultimately to two forms, extension and local movement—extension signifying matter, local movement signifying force. There is no such thing as empty space; there are no ultimate indivisible atoms; the universe is infinitely full of matter.
A fourth principle is, that the soul and matter are subsistences so fundamentally and absolutely distinct that they cannot act in reciprocal relations. This compelled Descartes to resort to his strained supposition that all correspondence or synchronism between bodily movements and mental or spiritual activities is merely reflex or automatic, or else is produced directly by act of Deity. For relief from this violent hypothesis, Leibnitz modified the Cartesian philosophy by his famous theory of a pre-established harmony.
Descartes did a great work, but it was not an abiding reconstruction: indeed, it was not construction so much as it was a dream—one of the grandest and most suggestive in the history of thought. Its audacious disparagement of the whole scholastic method startled Europe, upon the dead air of whose philosophy it came as a refreshing breath of transcendental thought. Its suggestions and inspirations are traceable as a permanent enrichment, though its vast fabric swiftly dissolved. The early enthusiasm for it in French literary circles and among professors in the universities of Holland scarcely outlasted a generation. Within a dozen years after the philosopher's death, the Cartesian philosophy was prohibited by ecclesiastical authorities and excluded from the schools. In the British Isles and in Germany the system has been usually considered as an interesting curiosity in the cabinet of philosophies. Yet the unity of all truth through relations vital, subtle, firm, and universal, though seen only in a vision of the night, abides when the night is gone.
With the impressive and noteworthy 'Discours de la Méthode' (Leyden, 1637), were published three essays supporting it: 'La Dioptrïque,' 'Les Météores,' 'La Géométrie.' Of his other works, the most important are 'Meditationes de Prima Philosophia' (Paris, 1641; Amsterdam, 1642), and 'Principia Philosophiæ' (Amsterdam, 1644). A useful English translation of his most important writings, with an introduction, is by John Veitch, LL.D.,—'The Method, Meditations, and Selections from the Principles' (Edinburgh, 1853; 6th ed., Blackwoods, Edinburgh and London, 1879). See also, English translations of portions of his philosophical works, by W. Cunningham (1877), Lowndes (1878), Mahaffy (1880), Martineau (1885), Henry Rogers, Huxley, and L. Stephen.
For his Life, see 'Vie de Descartes,' by Baillet (2 vols. 1691); 'Descartes sa Vie,' etc., by Millet (2 vols. 1867-71); 'Descartes and his School,' by Kuno Fischer (English translation, 1887).
OF CERTAIN PRINCIPLES OF ELEMENTARY LOGICAL THOUGHT
From the 'Discourse on Method'
As a multitude of laws often only hampers justice, so that a State is best governed when, with few laws, these are rigidly administered; in like manner, instead of the great number of precepts of which Logic is composed, I believed that the four following would prove perfectly sufficient for me, provided I took the firm and unwavering resolution never in a single instance to fail in observing them.