Whether prophecy can be natural?

Objections

Objection 1 : It would seem that prophecy can be natural. For Gregory says (Dial. iv, 26) that "sometimes the mere strength of the soul is sufficiently cunning to foresee certain things": and Augustine says (Gen. ad lit. xii, 13) that the human soul, according as it is withdrawn from the sense of the body, is able to foresee the future [*Cf. FP, Question [86], Article [4], ad 2]. Now this pertains to prophecy. Therefore the soul can acquire prophecy naturally.
Objection 2 : Further, the human soul's knowledge is more alert while one wakes than while one sleeps. Now some, during sleep, naturally foresee the future, as the Philosopher asserts (De Somn. et Vigil. [*De Divinat. per Somn. ii, which is annexed to the work quoted]). Much more therefore can a man naturally foreknow the future. Knowledge of the future by means of dreams, comes either from the revelation of spiritual substances, or from a corporeal cause, as stated above (Question [95], Article [6]), when we were treating of divination. Now both these causes are more applicable to a person while asleep than while awake, because, while awake, the soul is occupied with external sensibles, so that it is less receptive of the subtle impressions either of spiritual substances, or even of natural causes; although as regards the perfection of judgment, the reason is more alert in waking than in sleeping.
Objection 3 : Further, man, by his nature, is more perfect than dumb animals. Yet some dumb animals have foreknowledge of future things that concern them. Thus ants foreknow the coming rains, which is evident from their gathering grain into their nest before the rain commences; and in like manner fish foreknow a coming storm, as may be gathered from their movements in avoiding places exposed to storm. Much more therefore can men foreknow the future that concerns themselves, and of such things is prophecy. Therefore prophecy comes from nature.
Objection 4 : Further, it is written (Prov. 29:18): "When prophecy shall fail, the people shall be scattered abroad"; wherefore it is evident that prophecy is necessary for the stability of the human race. Now "nature does not fail in necessaries" [*Aristotle, de Anima iii, 9]. Therefore it seems that prophecy is from nature.