resulted in the integration of separate
bodies, to which they at the same time imparted a rotary motion. It is
such a hypothesis that Lucretius paints in his bold, impressionistic
colors.

But the development of mechanics paved the way for a definite scientific
theory, the so-called "nebular hypothesis," announced by La Place in
1796, and by the philosopher Kant at a still earlier date. Largely
through the Newtonian principle of the parallelogram of forces, the
present masses, orbits, and velocities were analyzed into a more
primitive process of concentration within a nebulous or highly diffused
aggregate of matter. And with the aid of the principle of the
conservation of energy this theory appears to make possible the
derivation of heat, light, and other apparently non-mechanical processes
from the same original energy of motion.

But a persistently philosophical mind at once raises the question of the
origin of this primeval nebula itself, with a definite organization and
a vast potential energy that must, after all, be regarded as a part of
nature rather than its source. Several courses are here open to
naturalism. It may maintain that the question of ultimate origin is
unanswerable; it may regard such a process of concentration as extending
back through an infinitely long past;[243:12] or, and this is the
favorite alternative for more constructive minds, the historical
cosmical process may be included within a still higher type of periodic
process, which is regarded as eternal. This last course has been
followed in the well-known synthetic naturalism of Herbert Spencer.
"Evolution," he says, "is the progressive integration of matter and
dissipation of motion." But such a process eventually runs down, and may
be conceived as giving place to a counter-process of devolution which
scatters the parts of matter and gathers another store of potential
motion. The two processes in alternation will then constitute a cosmical
system without beginning or end.

In such wise a sweeping survey of the physical universe may be thought
in the terms of natural science. The uniformitarian method in geology,
resolving the history of the crust of the earth into known processes,
such as erosion and igneous fusion;[244:13] and spectral analysis, with
its discoveries concerning the chemical constituents of distant bodies
through the study of their light, have powerfully reenforced this effort
of thought, and apparently completed an outl