As to the (Peripatetic) philosophers who assert that in a mixture only
the qualities mingle, while the material extension of both bodies are
only in juxtaposition, so long as the qualities proper to each of
them are spread throughout the whole mass, they seem to establish the
rightness of their opinion by attacking the doctrine which asserts that
the two bodies mutually interpenetrate in mixture.[60] (They object)
that the molecules of both bodies will finally lose all magnitude
by this continuous division which will leave no interval between the
parts of either of the two bodies; for if the two bodies mutually
interpenetrate each other in every part, their division must become
continuous. Besides, the mixture often occupies an extent greater than
each body taken separately, and as great as if mere juxtaposition
had occurred. Now if two bodies mutually interpenetrate totally, the
resulting mixture would occupy no more place than any one of them
taken separately. The case where two bodies occupy no more space than
a single one of them is by these philosophers explained by the air's
expulsion, which permits one of the bodies to penetrate into the
pores of the other. Besides, in the case of the mixture of two bodies
of unequal extent, how could the body of the smaller extend itself
sufficiently to spread into all the parts of the greater? There are
many other such reasons.