Summa contra Gentiles2.100 Chapter C. That separate substances know singulars

Since in the intellect of a separate substance the images of things are more universal than in our intellect, and more efficacious as a medium of knowledge, it follows that separate substances, through the images of material things, know material things not only according to their generic or specific nature, but also according to their individual nature. For seeing that the species of things in the intellect must needs be immaterial, they cannot, as existing in our intellect, be the principle of knowing singulars, which are individualized by matter: because the species of our intellect are of such limited virtue, that one leads to the knowledge only of one. Wherefore, just as the image of the generic nature cannot lead to the knowledge of genus and difference, so that the species be known thereby, in like manner the image of the specific nature cannot lead to the knowledge of the principles of individuality, which are material principles, so that the individual be known thereby in its singularity. On the other hand the image in the intellect of a separate substance, since it is of a more universal virtue, being at the same time one and immaterial, is able to lead to the knowledge of both the specific and the individualizing principles, so that through it the separate substance is able by its intellect to know not only the generic and specific natures, but also the individual nature. Nor does it follow that the form through which it knows is material; nor that such forms are infinite according to the number of individuals.

Further. Whatever a lower power can do, that can a higher power do, but in a higher way. Hence the lower power works by many instruments, whereas the higher power works by one only. For a power, the higher it is, the more is it consolidated and unified, whereas, on the other hand, the lower power is disunited and multiplied. Hence we observe that the one power of the common sense apprehends the various kinds of sensibles which the five external senses perceive. Now the human soul is lower than a separate substance in the order of nature: and it is cognizant of universals and singulars through two principles, namely, sense and intellect. Consequently a separate substance, being higher, knows both in a higher way by one principle, namely the intellect.

Again. The order in which the intelligible species of things reach our intellect is contrary to the order in which they reach the intellect of a separate substance. For they reach our intellect by a process of analysis, and by abstraction from material and individualizing conditions; so that it is not possible for us to know singulars through them. On the other hand they reach the intellect of a separate substance by a process of synthesis as it were: since it has intelligible species through its likeness to the first intelligible species, viz. the divine intellect, which is not abstracted from things, but productive of them. Now, it is productive not merely of the form but also of the matter which is the principle of individuality. Wherefore the species of the intellect of a separate substance represent the whole thing, not only the principles of its species, but also the principles of its individuality. Consequently we must not deny separate substances the knowledge of singulars, although our intellect is unable to know singulars.

Further. If the heavenly bodies are moved by the separate substances, according to the statement of philosophers, since separate substances act and move by their intellect, they must needs know the movable that they move: and this is some particular thing, for universals are immovable. Their positions also, which are changed by their movement, are singular things, and cannot be unknown to the substance which moves them by its intellect. We must, therefore, say that separate substances know singulars connected with these material things.