On The Holy Trinity by St. Augustine
Chapter 2.--Man Alone of Animate Creatures Perceives the Eternal Reasons of Things Pertaining to the Body.
2. And the beasts, too, are able both to perceive things corporeal from without, through the senses of the body, and to fix them in the memory, and remember them, and in them to seek after things suitable, and shun things inconvenient. But to note these things, and to retain them not only as caught up naturally but also as deliberately committed to memory, and to imprint them again by recollection and conception when now just slipping away into forgetfulness; in order that as conception is formed from that which the memory contains, so also the contents themselves of the memory may be fixed firmly by thought: to combine again imaginary objects of sight, by taking this or that of what the memory remembers, and, as it were, tacking them to one another: to examine after what manner it is that in this kind things like the true are to be distinguished from the true, and this not in things spiritual, but in corporeal things themselves; -- these acts, and the like, although performed in reference to things sensible, and those which the mind has deduced through the bodily senses, yet, as they are combined with reason, so are not common to men and beasts. But it is the part of the higher reason to judge of these corporeal things according to incorporeal and eternal reasons; which, unless they were above the human mind, would certainly not be unchangeable; and yet, unless something of our own were subjoined to them, we should not be able to employ them as our measures by which to judge of corporeal things. But we judge of corporeal things from the rule of dimensions and figures, which the mind knows to remain unchangeably.