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

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PHYSICS 453
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as are divisible by nature but are never actually divided
for why should the smaller resist division, when larger
bodies of similar substance do not do so ? No more can
the elements be produced from incorporeal substance, 1
from a body different from themselves ;
or
for if the latter
were not one of the elements, it could have no gravity or
natural locality, and hence would be a mathematical and
Hence
not a physical body, and would not exist in space.
we are driven to suppose that the elements are developed
from one another. 2 But this process can only be conceived
as one of transformation.
For if there were not a transformation
of the
elements, but only a putting forth of
something which they already contained complete within
themselves, one substance could not be entirely dissolved
into another, but an insoluble remnant would be left
and so any complete transmutation of substances, such
as is given in experience, would be impossible. 3
and fine
Coarse
materials could never be completely converted
into each other. 4 Lastly, how are we to imagine the
reciprocal influence of substances on one another, unless
they are capable of qualitative change ? Empedocles
and Democritus made bodies enter each other by means
of ' pores.' But not only can this hypothesis be dis-
1
As is proved at superfluous example, consists of a different
length, and with some obscurity, material or different atoms from
in the Be Casio, iii. 7, 305, a, lf> water, steam might be extruded
sqq.
from water, but water could not
- Be Ccelo, iii. 6. be wholly resolved into steam.
3 4
This objection is first brought Be Ccelo, iii. 4, 303, a 24,
against Anaxagoras in the Phyg, where the words vvo\ei\fiet y&p
i. 4, 187, b, 22 sqq. : iaBe Ccelo,iii. ciei, Sec, must mean 'since the
7, 305, b, 20 sqq. it is used against larger atoms would fail to obtain
all who explain material change as release,' so that in water, for exan
extrusion— in the latter case ample, a residuum would be left
with justice, since if steam, for which could not be turned into air.
ARISTOTLE
3d with, since bodies only require to be divisible,
aeed not be actually divided in order to
rocal influences ;
o bodies
experience
but it really serves no purpose, for,
cannot affect each other by contact, those
of them which interpenetrate by means of pores
not do so either. 1
•y of nature confined itself to
Therefore while the mechanical
a movement of the
entary ingredients in space, Aristotle maintained
qualitative alteration. Where the former had
lined apparent metamorphosis as a mere process of
»sion, Aristotle assumed the operation of real
ges under certain conditions.
His predecessors re-
;ed the reciprocal operation of bodies to pressure and
ilse :
he extended it to the internal nature of bodies,
eby they transform their primitive qualities,
t is precisely this process which he understands
action and passion ' in their stricter sense. 2 The
itions of such transformation, as of all
movement,
contained in the correlation of potentiality and
ility. When two things meet, of which one is
illy what the other is potentially, then, so far as
is the case, the latter is
patient, the former agent
i change is produced in the one, which proceeds from
Gen. et Corr. i. 8, 326, b, 6- rat {l6vov, oFo^ rb Aevicbv Kal rb 9ep-
9, 327, a, 7 sqq. /i.6v aWb. rb Kiveiv «rl irKeov rod
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Gen. et Corr. i. 6, 323, a, voie'iv iariv.
s
£ the movens is likewise Tbid. c. 9 init. : riva 8e rp6irov
7 motum, partly iijwnobile, inrdpxet rots ouo~t yevvyv Kal iroietv
must be true also of the /col irlaxeiv, Xeyw)j.ev \a06vres
> : Kal yap rb kivovv iroietv ri apxh" r)]V iroWdtcis i\fr\jxhi\v . ei
Kal rb iroiovv Kivetv. oil pAjv ydp eon rb /lev Suva/let t iari ical
Se Kaff 8