PHILOSOPHY OF NATURE—LEIBNITZ’S IDEAS. 41 
I. 
Leibnitz has thus led us on to the loftiest heights of 
thought, the furthest bounds of speculation. Let us now 
come down again with him to the special questions he has 
explored and transmitted to modern science, which still 
lacks the power to solve them all. We shall learn how 
serviceable that science has found the general principles 
settled by him as the grand laws of the world’s order. 
Leibnitz has the clearest and strongest sense of the diffusi- 
bility of life. He defines exactly the characteristic which 
lies at its base, that is, the incessant molecular replacement 
of matter in the permanence of active forms, namely, of 
souls. He holds that the minutest portion of matter con- 
tains a world of creatures, lives, animated beings, actuali- 
ties, souls. Every particle of matter is to be conceived of 
as a garden full of plants, ora pond full of fishes; but every 
twig of each plant, every limb of each animal, every drop 
in its humors, is again such a garden, or such a pond, full 
of decreasingly minute lives, similar in kind. All these 
bodies, he adds, move like rivers, in unresting flow. Por- 
tions pass into them, and pass out of them, incessantly. In 
this way the soul changes its bodies by very fine degrees, 
and is never suddenly stripped of its organs; vital proper- 
ties are continuous, while the matter of life is transitory. 
Leibnitz conjectured, consequently, that some animals must 
have the faculty of multiplying by scission, like plants. 
The discovery of polyps by Trembley, the facts of the mode 
of increase in vorticelli, parameciz, and bursars and opa- 
lines, since noticed, have justified the philosopher’s guess. 
Descartes regarded animals as machines, as soulless 
automata, made up of atoms the movements of which are 
codrdinated in the manner of those of plants. He denied 
them intelligence, and supposed that the sensibility and in- 
stinct noticed in them might be explained by purely me- 
chanical causes. Leibnitz does not admit that there are 
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