st hypothesis is assumed. We must dwell a good
deal more on this point. But let us first show more clearly the notion
of life to which we are leading up.

The mechanistic explanations, we said, hold good for the systems that
our thought artificially detaches from the whole. But of the whole
itself and of the systems which, within this whole, seem to take after
it, we cannot admit _a priori_ that they are mechanically explicable,
for then time would be useless, and even unreal. The essence of
mechanical explanation, in fact, is to regard the future and the past as
calculable functions of the present, and thus to claim that _all is
given_. On this hypothesis, past, present and future would be open at a
glance to a superhuman intellect capable of making the calculation.
Indeed, the scientists who have believed in the universality and
perfect objectivity of mechanical explanations have, consciously or
unconsciously, acted on a hypothesis of this kind. Laplace formulated it
with the greatest precision: "An intellect which at a given instant knew
all the forces with which nature is animated, and the respective
situations of the beings that compose nature--supposing the said
intellect were vast enough to subject these data to analysis--would
embrace in the same formula the motions of the greatest bodies in the
universe and those of the slightest atom: nothing would be uncertain for
it, and the future, like the past, would be present to its eyes."[19]
And Du Bois-Reymond: "We can imagine the knowledge of nature arrived at
a point where the universal process of the world might be represented by
a single mathematical formula, by one immense system of simultaneous
differential equations, from which could be deduced, for each moment,
the position, direction, and velocity of every atom of the world."[20]
Huxley has expressed the same idea in a more concrete form: "If the
fundamental proposition of evolution is true, that the entire world,
living and not living, is the result of the mutual interaction,
according to definite laws, of the forces possessed by the molecules of
which the primitive nebulosity of the universe was composed, it is no
less certain that the existing world lay, potentially, in the cosmic
vapor, and that a sufficient intellect could, from a knowledge of the
properties of the molecules of that vapor, have predicted, say the state
of the Fauna of Great Britain in 1869, with as much certainty as one can
say what wil