PROPOSITION XLVII.

In all material substances whose Forms are educed from the potentiality of Matter, the Matter is extrinsic genetic cause of the Haecceity of the Form, and, as a consequence, indirectly of the whole Composite.

Matter is here considered, not in its primeval state of indifference to all Forms, but as proximately disposed for the reception of such a particular Form and, by such disposition, divided off from other Matter, and individuated according to its capacity for individuation; i.e. so far as a determined receptivity, which is only half a being, can be individuated prior to its Act. This Proposition applies to all living, material, substances save man; because, in all of them, with this solitary exception, the substantial Form is evolved by process of natural law from the potentiality of Matter, as soon as the Matter is so ordered and disposed as to be proximately capable of substantial actuation.

The proof is not difficult. For that on which the substantial Form solely depends, in order of nature, for its existence and preservation, is extrinsic genetic cause of its Individuation. But the substantial Form solely depends in order of nature, (of course, all efficient Causation is excluded from our present consideration), on the Matter from which it is educed. Therefore, that Matter determines its Entity and, as a consequence, its Individuation.