Is it possible that fluid be blended with fluid in such a way that each penetrate the other through and through? or -- a difference of no importance if any such penetration occurs -- that one of them pass completely through the other?
Those that admit only contact need not detain us. They are dealing with mixture, not with the coalescence which makes the total a thing of like parts, each minutest particle being composed of all the combined elements.
But there are those who, admitting coalescence, confine it to the qualities: to them the material substances of two bodies are in contact merely, but in this contact of the matter they find footing for the qualities of each.
Their view is plausible because it rejects the notion of total admixture and because it recognizes that the masses of the mixing bodies must be whittled away if there is to be mixture without any gap, if, that is to say, each substance must be divided within itself through and through for complete interpenetration with the other. Their theory is confirmed by the cases in which two mixed substances occupy a greater space than either singly, especially a space equal to the conjoined extent of each: for, as they point out, in an absolute interpenetration the infusion of the one into the other would leave the occupied space exactly what it was before and, where the space occupied is not increased by the juxtaposition, they explain that some expulsion of air has made room for the incoming substance. They ask further, how a minor quantity of one substance can be spread out so as to interpenetrate a major quantity of another. In fact they have a multitude of arguments.
Those, on the other hand, that accept "complete transfusion," might object that it does not require the reduction of the mixed things to fragments, a certain cleavage being sufficient: thus, for instance, sweat does not split up the body or even pierce holes in it. And if it is answered that this may well be a special decree of Nature to allow of the sweat exuding, there is the case of those manufactured articles, slender but without puncture, in which we can see a liquid wetting them through and through so that it runs down from the upper to the under surface. How can this fact be explained, since both the liquid and the solid are bodily substances? Interpenetration without disintegration is difficult to conceive, and if there is such mutual disintegration the two must obviously destroy each other.
When they urge that often there is a mixing without augmentation their adversaries can counter at once with the exit of air.
When there is an increase in the space occupied, nothing refutes the explanation -- however unsatisfying -- that this is a necessary consequence of two bodies bringing to a common stock their magnitude equally with their other attributes: size is as permanent as any other property; and, exactly as from the blending of qualities there results a new form of thing, the combination of the two, so we find a new magnitude; the blending gives us a magnitude representing each of the two. But at this point the others will answer, "If you mean that substance lies side by side with substance and mass with mass, each carrying its quantum of magnitude, you are at one with us: if there were complete transfusion, one substance sinking its original magnitude in the other, we would have no longer the case of two lines joined end to end by their terminal points and thus producing an increased extension; we would have line superimposed upon line with, therefore, no increase."
But a lesser quantity permeates the entire extent of a larger; the smallest is sunk in the greatest; transfusion is exhibited unmistakably. In certain cases it is possible to pretend that there is no total penetration but there are manifest examples leaving no room for the pretence. In what they say of the spreading out of masses they cannot be thought very plausible; the extension would have to be considerable indeed in the case of a very small quantity [to be in true mixture with a very large mass]; for they do not suggest any such extension by change as that of water into air.
2. This, however, raises a problem deserving investigation in itself: what has happened when a definite magnitude of water becomes air, and how do we explain the increase of volume? But for the present we must be content with the matter thus far discussed out of all the varied controversy accumulated on either side.
It remains for us to make out on our own account the true explanation of the phenomenon of mixing, without regard to the agreement or disagreement of that theory with any of the current opinions mentioned.
When water runs through wool or when papyrus-pulp gives up its moisture why is not the moist content expressed to the very last drop or even, without question of outflow, how can we possibly think that in a mixture the relation of matter with matter, mass with mass, is contact and that only the qualities are fused? The pulp is not merely in touch with water outside it or even in its pores; it is wet through and through so that every particle of its matter is drenched in that quality. Now if the matter is soaked all through with the quality, then the water is everywhere in the pulp.
"Not the water; the quality of the water."
But then, where is the water? and [if only a quality has entered] why is there a change of volume? The pulp has been expanded by the addition: that is to say it has received magnitude from the incoming substance but if it has received the magnitude, magnitude has been added; and a magnitude added has not been absorbed; therefore the combined matter must occupy two several places. And as the two mixing substances communicate quality and receive matter in mutual give and take so they may give and take magnitude. Indeed when a quality meets another quality it suffers some change; it is mixed, and by that admixture it is no longer pure and therefore no longer itself but a blunter thing, whereas magnitude joining magnitude retains its full strength.
But let it be understood how we came to say that body passing through and through another body must produce disintegration, while we make qualities pervade their substances without producing disintegration: the bodilessness of qualities is the reason. Matter, too, is bodiless: it may, then, be supposed that as Matter pervades everything so the bodiless qualities associated with it -- as long as they are few -- have the power of penetration without disintegration. Anything solid would be stopped either in virtue of the fact that a solid has the precise quality which forbids it to penetrate or in that the mere coexistence of too many qualities in Matter [constitutes density and so] produces the same inhibition.
If, then, what we call a dense body is so by reason of the presence of many qualities, that plenitude of qualities will be the cause [of the inhibition].
If on the other hand density is itself a quality like what they call corporeity, then the cause will be that particular quality.
This would mean that the qualities of two substances do not bring about the mixing by merely being qualities but by being apt to mixture; nor does Matter refuse to enter into a mixing as Matter but as being associated with a quality repugnant to mixture; and this all the more since it has no magnitude of its own but only does not reject magnitude.
3. We have thus covered our main ground, but since corporeity has been mentioned, we must consider its nature: is it the conjunction of all the qualities or is it an Idea, or Reason-Principle, whose presence in Matter constitutes a body?
Now if body is the compound, the thing made up of all the required qualities plus Matter, then corporeity is nothing more than their conjunction.
And if it is a Reason-Principle, one whose incoming constitutes the body, then clearly this Principle contains embraced within itself all the qualities. If this Reason-Principle is to be no mere principle of definition exhibiting the nature of a thing but a veritable Reason constituting the thing, then it cannot itself contain Matter but must encircle Matter, and by being present to Matter elaborate the body: thus the body will be Matter associated with an indwelling Reason-Principle which will be in itself immaterial, pure Idea, even though irremoveably attached to the body. It is not to be confounded with that other Principle in man -- treated elsewhere -- which dwells in the Intellectual World by right of being itself an Intellectual Principle.