Thomas Aquinas

“ Hence Aristotle clearly places the ultimate felicity of man in the knowledge of separate substances, obtainable by speculative science; and not by being united to the active intellect as some imagined. ”

“ Therefore the passive intellect receives the intelligible object and the active intellect together; and the more numerous the intelligible objects received, so much the nearer do we come to the point of perfect union between ourselves and the active intellect; so much so that when we understand all the intelligible objects, the active intellect becomes one with us, and by its instrumentality we can understand all things material and immaterial. In this he makes the ultimate happiness of man to consist. ”

“ As material things, however, are intelligible only so far as we make them actually so by abstracting them from material conditions, it is clear that those substances are more intelligible in themselves whose nature is immaterial. ”

“ Hence, when it is perfectly united to us so that by its means we are able to understand perfectly, we also shall be able to understand separate substances, as in the present life through the medium of the passive intellect united to us, we can understand material things. Now he said that the active intellect is united to us, thus. For since we understand by means of both the active intellect and intelligible objects, as, for instance, we understand conclusions by principles understood ”

“ Created immaterial substances are not in the same natural genus as material substances, for they do not agree in power or in matter; but they belong to the same logical genus, because even immaterial substances are in the predicament of substance, as their essence is distinct from their existence. ”

“ Further, the fact that objects which are in themselves most sensible are not most felt by us, comes from sense being corrupted by their very excellence. But the intellect is not subject to such a corrupting influence from its object, as is stated De Anima iii, 4. ”

“ Sense knows bodies, whether superior or inferior, in the same way, that is, by the sensible acting on the organ. But we do not understand material and immaterial substances in the same way. The former we understand by a process of abstraction, which is impossible in the case of the latter, for there are no phantasms of what is immaterial. ”

“ Further, the human soul belongs to the genus of immaterial substances. But it can be understood by us through its act by which it understands material things. Therefore also other material substances can be understood by us, through their material effects. ”

“ Secondly, to be understood by us is not the end of separate substances: while only that is vain and purposeless, which fails to attain its end. It does not follow, therefore, that immaterial substances are purposeless, even if they are not understood by us at all. ”

“ Fourthly, this opinion is untrue, because it is hardly possible for anyone in this world to understand all material things: and thus no one, or very few, could reach to perfect felicity; which is against what the Philosopher says (Ethic. i, 9) , that happiness is a "kind of common good, communicable to all capable of virtue." Further, it is unreasonable that only the few of any species attain to the end of the species. ”

“ Thirdly, this opinion is untrue, because granted that, as above explained, the active intellect were united to us in substance, still it is not said that it is wholly so united in regard to one intelligible object, or two ”