It is likewise evident that a subsistent intelligence cannot be united with a body by any manner of contact, properly so called. For contact is only of bodies: those things are in contact, the extremities of which are together,* as points, or lines, or circumferences, which are the extremities of bodies.
Still there is one mode of contact whereby a subsistent intelligence may be mingled with a body. For natural bodies in touching one another involve a change, and thus are united together, not only in their quantitative extremities, but also by likeness of one same quality or form, the one in pressing its form on the other. And though, if we regard only quantitative extremities, the contact must be mutual in all cases, yet, if we consider action and passion, there will be found some cases of touching without being touched, and some cases of being touched without touching. Any cases that may be found of contact without contact in quantitative extremities must still be ca]led instances of contact, inasmuch as they are instances of action: thus we say that he who saddens another 'touches' him.* According to this mode of touch it is possible for a subsistent intelligence to be united to a body by contact: for subsistent intelligences act upon bodies and move them, being more highly actualised than bodies are.*
This contact is not quantitative but virtual, and differs from bodily contact in three respects. First, because in this contact the indivisible can touch the divisible, which cannot happen in bodily contact: for only that which is indivisible can be touched by a point,* whereas a subsistent intelligence, indivisible though it be, can touch a divisible quantity by acting upon it. The point and the subsistent intelligence are not indivisible in the same way. The point is indivisible as a term of quantity, and has a definite situation in a continuous surface, beyond which it cannot be thrown:* whereas a subsistent intelligence is indivisible by being outside of the category of quantity altogether: hence no indivisible element of quantity is marked out for contact with it. Secondly, because quantitative contact is only with extremities, but virtual contact is with the whole subject touched: for the subject is touched inasmuch as it is acted upon and moved; but that is inasmuch as it is in potentiality; and potentiality extends to the whole, not merely to the extremities of the whole: hence the whole is touched. From this appears a third difference: because in quantitative touch, which is of extremities, the touching body must be outside of the touched, and cannot pervade it, but is stopped by it;* whereas the virtual contact, which is proper to subsistent intelligences, reaching to the inmost recesses of things, makes the touching substance be within the touched and pervade it without let or hindrance. Thus then a subsistent intelligence may be united with a body by virtual contact.*
Elements united by such contact are not absolutely one: they are one in action and in being acted upon, which does not involve absolute oneness of being. Such absolute oneness may be in three ways: in the way of indivisibility, in the way of continuity, and in the way of natural unity. Now out of a subsistent intelligence and a body there cannot be made an indivisible unity: it must be a compound of two things. Nor again a continuous unity, because the parts of a continuum are quantitative. It remains to be enquired whether out of a subsistent intelligence and a body there can result such a unity as means oneness of nature.* But out of two permanent elements there results no being one by nature except that which results of the union of substantial form with matter: for out of substance and accident there results no being one by nature, for the nature or essence of 'man' and 'whiteness' is not the same.* This question then remains to be studied, whether a subsistent intelligence can be the substantial form of any body. Looking at the matter argumentatively, it might seem that the thing is impossible.
Arg. 1. Of two actually existent substances no one being can be made: for the actuality of every being is that whereby it is distinguished from another being. But a subsistent intelligence is an actually existing substance: so likewise is a body. Apparently therefore no one being can be made of a subsistent intelligence and a body.
Arg. 2. Form and matter are contained under the same genus: for every genus is divided into actual and potential. But a subsistent intelligence and a body are of different genera.
Arg. 3. All that is in matter must be material. But if subsistent intelligence is the form of a body, the being of such intelligence must be in matter: for there is no being of the form beyond the being of the matter. It follows that a subsistent intelligence could not be immaterial, as supposed.
Arg. 4. It is impossible for anything having its being in a body to be apart from the body. But intelligence is shown to be apart from the body, as it is neither the body itself nor a bodily faculty.*
Arg. 5. Whatever has being in common with the body, must also have activity in common with the body: for the active power of a thing cannot be more exalted than its essence. But if a subsistent intelligence is the form of a body, one being must be common to it and the body: for out of form and matter there results absolute unity, which is unity in being. At that rate the activity of a subsistent intelligence, united as a form to the body, will be exerted in common with the body, and its faculty will be a bodily (or organic) faculty: positions which we regard as impossible.
(Chap. LXIX). It is not difficult to solve the objections alleged against the aforesaid union.
Reply 1. The first objection contains a false supposition: for body and soul are not two actually existing substances, but out of the two of them is made one substance actually existing: for a man's body is not the same in actuality when the soul is present as when it is absent: it is the soul that gives actual being.*
Reply 2. As for the second objection, that form and matter are contained under the same genus, it is not true in the sense that both are species of one genus, but inasmuch as both are elements of the same species. Thus then a subsistent intelligence and a body, which as separate existences would be species of different genera, in their union belong to one genus as elements of the same.
Reply 3. Nor need a subsistent intelligence be a material form, notwithstanding that its existence is in matter: for though in matter, it is not immersed in matter, or wholly comprised in matter.
Rep!y 4. Nor yet does the union of a subsistent intelligence with a body by its being that body's form stand in the way of intelligence being separable from body.* In a soul we have to observe as well its essence as also its power. In point of essence it gives being to such and such a body, while in point of power it executes its own proper acts. In any activity of the soul therefore which is completed by a bodily organ, the power of the soul which is the principle of that activity must bring to act that part of the body whereby its activity is completed, as sight brings the eye to act. But in any activity of the soul that we may suppose not to be completed by any bodily organ, the corresponding power will not bring anything in the body to act; and this is the sense in which the intellect is said to be 'separate,' -- not but that the substance of the soul, whereof intellect is a power, or the intellectual soul, brings the body to act, inasmuch as it is the form which gives being to such body.
Reply 5. Nor is it necessary, as was argued in the fifth place, that if the soul in its substance is the form of the body, its every operation should be through the body, and thus its every faculty should be the actuation of some part of the body: for the human soul is not one of those forms which are entirely immersed in matter, but of all forms it is the most exalted above matter: hence it is capable of a certain activity without the body, being not dependent on the body in its action, as neither in its being is it dependent on the body.
2.55 : That Subsistent Intelligences are Imperishable
2.57 : Plato's Theory of the Union of the Intellectual Soul with the Body