f the physical sciences, the term
cosmology has come more definitely to signify the _philosophy of
nature_. It embraces such an examination of space, time, matter,
causality, etc., as seeks to answer the most general questions about
them, and provide for them in the world thought of as most profoundly
real. Such a study receives its philosophical character from its
affiliation with ontology, as the latter would find its application in
cosmology.

[Sidenote: Mechanical and Teleological Cosmologies.]

Sect. 63. But in addition to the consideration of the various parts of
nature, cosmology has commonly dealt with a radical and far-reaching
alternative that appeared at the very dawn of metaphysics. Differences
may arise within a world constituted of a single substance or a small
group of ultimate substances, by changes in the relative position and
grouping of the parts. Hence the virtue of the conception of motion. The
theory which explains all differences by motions of the parts of a
qualitatively simple world, is called _mechanism_. Another source of
change familiar to naive experience is _will_, or the action of living
creatures. According to the mechanical theory, _changes occur on account
of the natural motions of the parts of matter_; according to the latter
or _teleological_ conception, _changes are made by a formative agency
directed to some end_. Among the early Greek philosophers, Leucippus was
an exponent of mechanism.

"He says that the worlds arise when many bodies are collected
together into the mighty void from the surrounding space and
rush together. They come into collision, and those which are
of similar shape and like form become entangled, and from
their entanglement the heavenly bodies arise."[161:11]

Anaxagoras, on the other hand, was famed for his doctrine of the Nous,
or Intelligence, to whose direction he attributed the whole process of
the world. The following is translated from extant fragments of his
book, "+peri physeo:s+":

"And Nous had power over the whole revolution, so that it
began to revolve in the beginning. And it began to revolve
first from a small beginning; but the revolution now extends
over a larger space, and will extend over a larger still. And
all the things that are mingled together and separated off and
distinguished are all known by the Nous. And Nous set in order
all things that were to be and that were, and