60 NATURE AND LIFE. 



special way. Geometry and mechanics, in their specula- 

 tion, separate material points from forces, while biology 

 teaches us to keep them bound together in an indestructible 

 and necessary unity. The science of motions and of the 

 forms they take, shows us only the outside of the energy of 

 the universe. The science of life, on the contrary, unveils 

 to us its throbbing heart and its splendid plan. Such is 

 the measureless and priceless service it yields to knowledge 

 and to discussion. Descartes, and those who attempt in 

 our day to revive his system by deducing physics from 

 mechanics, and physiology from physics, by explaining the 

 higher through the lower, as Auguste Comte says, by for- 

 bidding anj^ endeavor to conceive first principles by the aid 

 of last principles all those philosophers, whatever their 

 merit in other respects, have misunderstood the lessons 

 yielded by the living being in its twofold physiological and 

 psychological relation. The evidences of soul making one 

 and the same with life might have displayed to their view 

 images of the soul and of life throughout the universe, 

 instead of blind and misleading geometrism. They would 

 have understood that ciphers and diagrams do not solve 

 .every thing, that computation is not the only method. 

 That which does solve every thing is the soul, because it 

 alone embraces every thing, or at least discovers in itself 

 alone, rapt in abstraction, instinctive secret affinities with 

 all. Besides, the certain and enduring fame of Descartes 

 is great enough to permit us, without fear of dimming its 

 deserved lustre, to pronounce sentence of impotence upon 

 any attempts made in our day toward the introduction into 

 natural philosophy of false principles borrowed from his 

 teachings. The guidance and inspiration which modern 

 biological science owes to them attest the increasing honor 

 paid to the ideas of Leibnitz. 1 



1 This article, written during the siege of Paris at the ambulance of 

 Conflans, where I was serving as physician, having access only to a few 



