REFUTATION OF ANAXÁGORAS AND DEMOCRITUS.
1. The subject of the present consideration is mixture to the point of total penetration of the different bodies. This has been explained in two ways: that the two liquids are mingled so as mutually to interpenetrate each other totally, or that only one of them penetrates the other. The difference between these two theories is of small importance. First we must set aside the opinion of (Anaxágoras and Democritus), who explain mixture as a juxtaposition, because this is a crude combination, rather than a mixture. Mixture should render the whole homogeneous, so that even the smallest molecules might each be composed of the various elements of the mixture.
REFUTATION OF ARISTOTLE AND ALEXANDER OF APHRODISIAS.
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 Tightness of their opinion by attacking the doctrine which asserts that the two bodies mutually interpenetrate in mixture. (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 expuls;on, 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.
REFUTATION OF THE STOICS.
We now pass to the opinions of (Zeno and the other Stoic) philosophers, who assert that two bodies which make up a mixture mutually interpenetrate each other totally. They suppport this view by observing that when the bodies interpenetrate totally, they are divided without the occurrence of a continuous division (which would make their molecules lose their magnitude). Indeed, perspiration issues from the human body without its being divided or riddled with holes. To this it may be objected that nature may have endowed our body with a disposition to permit perspiration to issue easily. To this (the Stoics) answer that certain substances (like ivory), which when worked into thin sheets, admit, in all their parts, a liquid (oat-gruel) which passes from one surface to the other. As these substances are bodies, it is not easy to understand how one element can penetrate into another without separating its molecules. On the other hand, total division must imply mutual destruction (because their molecules would lose all magnitude whatever). When, however, two mingled bodies do not together occupy more space than either of them separately (the Stoics) seem forced to admit to their adversaries that this phenomenon is caused by the displacement of air.
EXPLANATION OF MIXTURE THAT OCCUPIES MORE SPACE THAN ITS ELEMENTS.
In the case where the compound occupies more space than each element separately, it might (though with little probability), be asserted, that, since every body, along with its other qualities, implies size, a local extension must take place. No more than the other qualities could this increase perish. Since, out of both qualities, arises a new form, as a compound of the mixture of both qualities; so also must another size arise, the mixture combining the size out of both. Here (the Peripatetics) might answer (the Stoics): “If you assert a juxtaposition of substances, as well as of the masses which possess extension, you are actually adopting our opinions. If however one of the masses, with its former extension, penetrate the entire mass of the other, the extension, instead of increasing, as in the case where one line is added to another by joining their extremities, will not increase any more than when two straight lines are made to coincide by superimposing one on the other.”
CASE OF MIXTURE OF UNEQUAL QUANTITIES.
The case of the mixture of a smaller quantity with a greater one, such as of a large body with a very small one, leads (the Peripatetics) to consider it impossible that the great body should spread in all the parts of the small one. Where thé mixture is not evident, the (Peripatetics) might claim that the smaller body does not unite with all the parts of the greater. When however the mixture is evident, they can explain it by the extension of the masses, although it be very doubtful that a small mass would assume so great an extension, especially when we attribute to the composite body a greater extent, without nevertheless admitting its transformation, as when water transforms itself into air.