PHILOSOPHY OF NATURE—LEIBNITZ’S IDEAS. 37 
relation established beforehand in every substance in the 
universe which creates its general communion, and creates 
particularly the union between soul and body. We may 
hence understand how the soul has its seat in the body 
by near and direct presence, for it is in it as unity is in 
multitude. The soul, a thinking monad, acts in conso- 
nance with inferior but still vital monads, which, concur- 
rently with it, are manifested by the organized substance in 
which thought has its seat. The soul is in relations with 
the lower activities of life, as they are with the still duller 
activities of mere matter, in a companionship which is not 
a dependence. 
We must now rise higher, and study the relations and 
the communion between monads in the universe. Three 
principles, that of preéstablished harmony, that of con- 
tinuity, and that of the sufficient reason, are here the basis 
of Leibnitz’s philosophy. Preéstablished harmony ex- 
presses nothing else than the combination of all monads in 
the universe. Our mind perceives an infinity of relations 
among them, of which it does not grasp the physical ne- 
cessity. It does not know why two monads act in concert, 
or the one upon the other, to bring about some special 
results. It cannot explain how monads of a lower order 
exert influence over those of a higher order, those of the 
body on those of the soul, and reciprocally. In a word, as 
Hume demonstrates, we perceive no logical and necessary 
connection between phenomena which follow each other in 
the successive relations of cause and effect. Yet we are 
certain that no single molecule in the world is alien to the 
rest, that not one is isolated from the whole, that all are 
conjoint and act together in the whirl of general existence. 
We remark that every effect depends on an infinity of 
causes, and that every cause has an infinity of effects. The 
concourse, the common action, the consensus of all these 
monads toward a regular order, manifestly prove an estab- 
