b. Solution of the Second Doubt

64. And from this [n.63] the answer is plain to the second doubt [n.50]; for I say that the inherence of whiteness too is not the same as whiteness.

65. And when proof is given through the relation of the creature to God [n.50], I say the case is not alike, because of the major previously set down for this third conclusion [n.39]; for no relation to an extrinsic cause is identical with the thing caused save the relation that is to the first cause, because of the fact that the first cause can create any creature at all without any other extrinsic cause at all.

66. And when the argument about the definition is given [n.50], it would prove rather that an accident should not be defined by the subject, because stone or horse are not defined by God, therefore neither is accident by subject. Nevertheless, although God is the sort of cause without which it is impossible and a contradiction for a stone or a horse to exist, yet it is not so in the case of a subject with respect to an accident.

67. But I reply: the identity, or non-identity, of a respect with the foundation is not a reason that the term of respect should fall into the definition of the foundation as something added.

68. What else then?

I reply that neither is dependence an essential and necessary cause that the term of the dependence be added in the definition of the depending foundation; for then God would more be posited in the definition of any caused thing than substance in the definition of accident. But the cause is that no form can have a satisfyingly complete concept unless that of which it is the form be understood along with it; but a definition expresses the perfect concept of the defined thing; and therefore, however much the essential features of a form be expressed without that of which it is the form, and although the quiddity of it be indicated, yet there would not be a perfect concept satisfying the intellect, and so not a definitive concept either. But if a caused thing that is in itself some subsistent composite is conceived in itself, the intellect rests there, not seeking anything else to understand along with it.

69. And if you object that there is therefore equal necessity for a substantial form to be defined by something added as for an accident as well, I reply that there is a necessity on both sides. The point is plain from the Philosopher in defining the soul, On the Soul 2.1.412a19-21, where he at once posits the body (which is what is perfectible by the soul), or the whole composite (of which the soul is part). Nor does he posit anything pertaining to the essence of the soul save only that it is act, which signifies the respect of the soul to that of which it is the form. But there is not a like addition here and there, because in the definition of a substantial form is added something that, with it, makes it per se one, or of which it is a per se part (I give the disjunction because of the diverse way of saying that a form is defined, through matter or through the whole); but in the definition of an accidental form is added something with which it does not make a per se one, nor of which it is per se part.