G. F. Becker— Kant as a Natural Philosopher. 99 



the highest geometrical precision and mathematical infallibility 

 can never be demanded from a treatise of this description. If 

 the system is founded on analogies and agreements, developed 

 according to the rules of credibility and in a logical manner, it 

 satisfies the conditions which its object demands." In judging 

 of Kant's theory, allowance must be made for the faulty data 

 at his disposal, particularly in respect to the masses of the 

 planets, and for the undeveloped state of astronomical science. 

 I know of no more striking way to emphasize the remoteness 

 of the period when the theory was published than to note that 

 in 1755 Lagrange was 19 years old, William Herschel 17, and 

 Laplace 6. Kant was not always right, and indeed he himself 

 threw doubt on certain of his results, but some of his great 

 successors fell into some of the same pitfalls. That many of 

 his theories are held to-day shows the keenness of his scientific 

 faculty, and almost excites a regret that he did not remain 

 loyal to Urania. It is doubtful, however, whether he could 

 have been restrained from metaphysical inquiries. There is a 

 small group of men, naturalists by instinct, who seem irre- 

 sistibly compelled to include among the phenomena forming 

 the object of their inquiries the mechanism of the intellect 

 and the relations of ideas. Such are Aristotle, Bacon, Des- 

 cartes, Kant and a living English philosopher. 



Kant was not the first philosopher to speculate on the origin 

 of the heavenly bodies, though he was the first Newtonian to 

 do so. If one leaves aside some vague speculations of the 

 ancients, there can be no doubt that the first germ of the nebu- 

 lar hypothesis is to be found in Descartes' Principles of 

 Philosophy, published in 1644 (43 years before Newton's 

 Principia). It may briefly and imperfectly be represented as 

 follows. The content of the universe is divisible into three 

 categories.* The first corresponds nearly to the luminiferous 

 ether of the present day and its agitation produces light, the 

 second answers approximately to gas, the third to solid or 

 liquid substances. This last Descartes calls " opaque matter." 

 In the beginning these materials were almost uniformly dis- 

 tributed through space and possessed motion in nearly equal 

 amounts.f The nebulous mass was divided into patches of 

 common rotation, or the famous Cartesian vortices. In each 

 vortex there were subordinate vorticules, eddies in a whirlpool. 

 The motion of rotation was most rapid at the center, di min- 

 xes principes de la Philosophic, Cousin's edition. 1824, part 3, sec. 52. The 

 three categories are summarized as ''etre lumineux, etre transparent, et etre 

 opaque ou obscur." 



f In all, '' Autant de mouvement qu'il y en a encore a present dans le monde." 

 (Part 3, sec. 46). Descartes supposed the momentum of the universe a fixed 

 quantity. Leibnitz, I believe, was the first to assert the constancy of the total 

 energy. 



