PHILOSOPHY OF NATURE—LEIBNITZ’S IDEAS. 59 
mg of mass multiplied by momentum, and active force as 
the product mv” of mass multiplied by the square of the 
velocity. Let us in the first place remark how highly un- 
philosophical it is to regard the most simple and irredu- 
cible things in the world as products, to confine within the 
strict limits of a one-term statement the living pulsations 
of the infinite and the absolute in things. In the next 
place, the attempt to define force by any calculation of 
figures seems like aping a man who should insist that the 
arrow-marks used in geometrical diagrams to denote the 
direction of forces were exact likenesses of the forces 
themselves. The cipher is the sign of quantity, the line 
that of motion. Force is something else than quantity, a 
very different thing from motion. But let us grant these 
definitions are proper: the question still remains, What are 
the causes that produce acceleration, velocity, resistance, 
in the mass? Now, it is impossible to avoid connecting 
these causes with some principle higher than geometrics, 
with a spontaneity more or less resembling that effort 
which in ourselves goes before action. We are thus al- 
ways brought back, whether we would or not, to active 
monads, whose infinite varieties, infinite relations, and in- 
finite interminglings, bring forth all. The accomplished 
writers we speak of will in vain strive to reduce to measured 
fractions of space and of time that which is in its essence 
the opposite of space and time—force; and the attempt is 
futile to prove that we have not a consciousness of the 
dynamic resistance of the elements of the world as clear 
as that which we have of our own individual effort to 
counterpoise it. 
It is easy to point out the cause of such specious abuse 
of geometrical and mechanical considerations in natural 
philosophy. It grows out of ignorance of those biological 
facts by which the profound spontaneity, and the reality 
of forces consubstantial with bodies, are revealed in a 
