ARISTOTLE AND THE EARLIER PERIPATETICS vol.I by Eduard Zeller, B.F.C.Costelloe 1897

;
'
with
without changing its place as a whole. 1
PHYSICS 441
It is the measure
for all other movement. It alone is entirely uniform,
movement rapidity increases in
whereas in rectilinear 2
proportion to the distance from the starting-point. 3
How
this eternal rotation is brought about by the operation
of the primum mouens 4 we have already shown.
Important though movement in space is, as the
most primitive kind of change on which all
others are
dependent, Aristotle cannot agree with the mechanical
theory of physics in merging all forms of change in this
one,andiu assuming only the combination and separation,
while rejecting the transmutation, of materials.
questions arise upon this point.
Three
Is there a qualitative
distinction between sorts of matter ? Is there a qualitative
alteration of materials ? Is there such a combination
of materials as to cause the change of their
1
Phys. viii. 9, 265, b, 1 ; of.
p. 398, i.
- Those, namely, which Aristotle
treats as the natural motions
of elementary bodies: in other
words, the downward motion of
heavy, and the upward motion, of
light bodies. With forcible movements
the opposite is the case.
3
Physs. viii. 9, 265, b, 8 sqq.
* The seventh book of the
Physics is passed over in the
above account, because it was not
originally a part of the work (see
p. 8 L, n. 2, mprd). Its contents are
as follows. After it has been
explained in c. 1 that every movement
must have its source in a
primum mm;ens, and in c. 2 (see
p. 386, n. 3, and p. 423, n.\,adfin.)
that the latter must move along
with the motion, c. 3 goes on to
show that dWoiwtris concerns only
the sensible qualities of things;
c. i inquires in what case two
movements are commensurable,
and c. 5 finally proves that the
same force moves half the mass in
the same time twice as far, in half
the time the same distance as the
whole ; likewise that the same
mass is moved, by the same force,
in the same time, the same distance,
in half the time half the
distance, while half the mass is
moved by half the force the same
distance ; on the other hand, it
does not follow that twice the
mass is moved by the same force
half as far as half the mass, or
the same mass by half the force
half as far as by the whole force
for the force may not perhaps be
able to move it at all. The same
is true of the other kinds of
change.
ARISTOTLE
ties ? The Atomists answered all three of these
bions, Anaxagoras and Empedocles at least the
id and the third, in the negative. Aristotle feels
elf obliged to answer all
affirmatively, combating
nechanical theory of his predecessors, and seeking
olution of their difficulties in the peculiar tenets of
>wn system. That he wholly succeeded in this
lpt the natural science of our day will certainly
e to admit, and will even be frequently inclined,
Bacon, 1 to take the part of Democritus against
LSt
Yet this is just a case in which we have to guard
a too hasty criticism of a man who occupies one
e first places among the scientific investigators as
is the philosophers of antiquity.
In order to form
ripartial judgment of Aristotle in his contest with
lechanical theory of physics, and to
appreciate his
riews, we must never forget that we have not here
the atomistic philosophy of our days, but
that of Democritus, which differed from it tota
Aristotle, like his opponents, possessed nothing
be scantiest rudiments of the methods and proi
of
observation which we have to so boundless
:tent at our command. He had to define the
ntary physical conceptions of an age whose obseris
did not extend beyond the reach of the naked
tnd whose experiments were confined to a few
3 and for the most part very unreliable empirical
ises. Of all 2 our mathematical, optical, and
:. Kuno Fischbe, Franz ences (Arist. ThierJtunde, 410
262 sqq. (Eng. tr.). sq.) to Aristotle's method in test-
'.
also JBeandis, ii. b, 1213 ing heat.
sq., and Meyer's refer-