view of Plato and the Pythagoreans that {292} the elements
are composed of geometrical figures. And connected with
this is his repudiation of the mechanical hypothesis that all
quality is founded upon quantity, or upon composition and
decomposition. Quality has a real existence of its own. He
rejects, also, the view that space is a physical thing. If this
were true, there would be two bodies occupying the same
place at the same time, namely the object and the space
it fills. Hence there is nothing for it but to conceive space
as limit. Space is, therefore, defined as the limit of the
surrounding body towards what is surrounded. As we shall
see later, in another connexion, Aristotle did not regard
space as infinite.
Time is defined as the measure of motion in regard to what
is earlier and later. It thus depends for its existence upon
motion. If there were no change in the universe, there would
be no time. And since it is the measuring or counting of
motion, it also depends for its existence upon a counting
mind. If there were no mind to count, there could be no
time. This presents difficulties to us, if we conceive that
there was a time when conscious beings did not exist. But
this difficulty is non-existent for Aristotle, who believed
that men and animals have existed from all eternity. The
essentials of time, therefore, are two: change and conscious-
ness. Time is the succession of thoughts. If we object that
the definition is bad because succession already involves
time, there is doubtless no answer possible.
As to the infinite divisibility of space and time, and the
riddles proposed thereupon by Zeno, Aristotle is of opinion
that space and time are potentially divisible {293}ad in-
finitum, but are not actually so divided. There is nothing
to prevent us from going on for ever with the process of
division, but space and time are not given in experience as
infinitely divided.After these preliminaries, we can pass on to consider the
main subject of physics, the scale of being. We should no-
tice, in the first place, that it is also a scale of values. What
is higher in the scale of being is of more worth, because the
principle of form is more advanced in it. It constitutes also
a theory of development, a philosophy of evolution. The
lower develops into the higher. It does not, however, so de-
velop in time. That the lower form passes in due time into
a higher form is a discovery of modern times. Such a con-
ception was impossible for Aristotle. For him, genus and
species are eternal. They have neither beginning nor end.
Individual men are born and die, but the species man never
dies, and has always existed upon the earth. The same is
true of plants and animals. And since man has always ex-
isted, he cannot have evolved in time from a lower being.
There is no room here for Darwinism. In what sense, then,
is this a theory of development or evolution? The process
involved is not a time-process, it is a logical process, and
the development is a logical development. The lower always
contains the higher potentially. The man is in the ape ide-
ally. The higher, again, contains the lower actually. The
man is all that the ape is, and more also. What is merely
implicit in the lower form is explicit in the higher. The form
which is dimly seen struggling to light in the lower, has re-
alized itself in the higher. The higher is the same thing as
the lower, but it is the same thing in a more {294} evolved