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

EHFSICS 443
•
physical instruments, he possessed only the rule and
compasses, together with the most imperfect substitutes
for some few others. Chemical analysis, correct measurements
and weights, and a thorough application of
mathematics to physics, were unknown. The attractive
force of matter, the law of gravitation, electrical
phenomena,
the conditions of chemical combination, pressure
of air and its effects, the nature of light, heat,
combustion, &c.—in short, all the facts on which the
physical theories of modern science are based, were
wholly, or almost wholly, undiscovered.
It would have
been more than a miracle, if under such circumstances
Aristotle had developed views in natural
which we could have availed
ourselves without alteration
at the present time.
philosophy of
It is the business of a history
to show how he explained phenomena consistently with
the position of knowledge in his own day. 1
None of the ancient systems presents so pure a form
of mechanical physics as the atomic, to which the theory
of the elements adopted by Plato from Philolaus is
closely allied.
Both deny qualitative variety in matter,
and consider differences of shape and magnitude as the
only original and real distinction. Aristotle opposes
this view, not merely because it maintains the existence
of infinitely small bodies or superficies, but also because
it denies specific difference in matter. In both respects,
according to his judgment, the weaknesses of
the Platonic theory are most striking. 2 It contradicts
mathematics, because it
regards bodies as composed of
superficies, which brings us logically to the assumption
1
Cf. supra, p. 262 sq.
2 Cf. ZelleS, Platon. Stud. . 270 sq.
'
indivisible
i
ARISTOTLE
lines , ' nay, further, to the resolution of
agnitudes into points. 2 Again it destroys the divisility
of bodies. 3
Moreover, the figures of the elements
isumed by Plato do not fill the space within the world,
id yet he allows no vacuum. 4 Lastly, it is impossible
form any coherent bodies out of them. 6 Nor are the
fficulties which beset this theory from the point of
ew of physics less important. For how can bodies
hich have weight consist of surfaces which have
me ? 6 And how, according to this hypothesis, could
Le specific gravity or levity of the single elements be
oduced ? Fire would have to become heavier and
cend more slowly in proportion to its bulk ; much
r would be heavier than a little water. 7
Again, while
jperience shows that all the elements are mutually
ansmutable, Plato only admits this with respect to
.e three just mentioned; 8 even in their case diffiilties
arise from the circumstance that superfluous
Plato, indeed, and Xenocra- are not balls or pyramids.
1
5 actually adopted this assumpl
Ibid. c. 8 init. ; cf. Zell.
in ; cf. Zell. Ph. d. Gr. pt. i. Ph. d. Gr. pt. i. 679, 3.
i.
807, 2 ad fin. 868.
5 Ibid. 306, b, 22 sqq.
2 6
Be Ccelo, iii. 1, 299, a, 6, 300, Be Casio, iii. 1, 299, a, 25 sqq.
7, c. 7, 306, a, 23. Cf. Gen. et b, 31 sqq. (where, however, we