. But if we leave out of the
two doctrines what breathes life into them, if we retain the skeleton
only, we have before us the very picture of Platonism and
Aristotelianism seen through Cartesian mechanism. They present to us a
systematization of the new physics, constructed on the model of the
ancient metaphysics.

What, indeed, could the unification of physics be? The inspiring idea of
that science was to isolate, within the universe, systems of material
points such that, the position of each of these points being known at a
given moment, we could then calculate it for any moment whatever. As,
moreover, the systems thus defined were the only ones on which the new
science had hold, and as it could not be known beforehand whether a
system satisfied or did not satisfy the desired condition, it was useful
to proceed always and everywhere _as if_ the condition was realized.
There was in this a methodological rule, a very natural rule--so
natural, indeed, that it was not even necessary to formulate it. For
simple common sense tells us that when we are possessed of an effective
instrument of research, and are ignorant of the limits of its
applicability, we should act as if its applicability were unlimited;
there will always be time to abate it. But the temptation must have been
great for the philosopher to hypostatize this hope, or rather this
impetus, of the new science, and to convert a general rule of method
into a fundamental law of things. So he transported himself at once to
the limit; he supposed physics to have become complete and to embrace
the whole of the sensible world. The universe became a system of points,
the position of which was rigorously determined at each instant by
relation to the preceding instant and theoretically calculable for any
moment whatever. The result, in short, was universal mechanism. But it
was not enough to formulate this mechanism; what was required was to
found it, to give the reason for it and prove its necessity. And the
essential affirmation of mechanism being that of a reciprocal
mathematical dependence of all the points of the universe, as also of
all the moments of the universe, the reason of mechanism had to be
discovered in the unity of a principle into which could be contracted
all that is juxtaposed in space and successive in time. Hence, the whole
of the real was supposed to be given at once. The reciprocal
determination of the juxtaposed appearances in space was explained by