Here Thomas seems rationally to recognize the limits upon reason in discovering the divine nature. In the regions of faith, reason’s feet lack the material footing upon which to mount. So Thomas would assert. But will he stand to his assertion? The shadowy line between reason and faith wavers with him. At least so it seems to us, for whom ontological reasoning has lost reality, and who find proofs of God not so much easier than proofs of the Trinity. But Thomas and the other scholastics dwelt in the region of the metaphysically ideal. To them it was not only real, but the most real; and it was so natural to step across the line of faith, trailing clouds of reason. The feet of such as Thomas are as firmly planted on the one side of the line as on the other. And now, as it might also seem, Thomas, having thus formally reserved the realm of faith, quickly steps across the line, to undertake a tremendous metaphysical exposition of the Trinity, of the distinctions between its Persons, of their properties, respective functions, and relationships; and all this is carried on largely in the categories of Aristotelian philosophy. Yet is he not still consistent with himself? For he surely did not conceive the elements of his discussion to lie in the lucubrations or discoveries of the natural reason; but in the data of revelation, and their explanation by saintly doctors. And was not he also a vessel of their inspiration, a son of faith, who might humbly hope for the light of grace, to transfigure and glorify his natural powers in the service of revealed truth?
Thomas’s ideal is intellectual, and yet ends in faith. His intellectual interests, by faith emboldened, strengthened, and pointed heavenward, make on toward the realisation of that intellectual beatitude which is to be consummate hereafter, when the saved soul’s grace-illumined eye shall re-awaken where it may see face to face.
III
Knowledge, then, supplemented in this life by faith, is the primary element of blessedness. We now turn our attention to the forms of knowledge and modes of knowing appropriate to the three rational substances: God, angel, man. The first is the absolute incorporeal being, the primal mover, in whom there is no potentiality, but actuality simple and perfect. The second is the created immaterial or “separated” substance, which is all that it is through participation in the uncreate being of its Creator. The third is the composite creature man, made of both soul and body, his capacities conditioned upon the necessities of his dual nature, his sense-perception and imagination being as necessary to his knowledge, as his rational understanding; for whom alone it is true that sense-apprehension may lead to the intelligible verities of God: “etiam sensibilia intellecta manuducunt ad intelligibilia divinorum.”[593]
The earlier Quaestiones of Pars prima, on the nature of God, lead on to a consideration of God’s knowledge and ways of knowing. Those Quaestiones expounded the qualities of God quite as far as comported with Thomas’s realization of the limitation of the human capacity to know God in this life. Quaestio iii. upon the Simplicitas of God, shows that God is not body (corpus); that in Him there is no compositeness of form and material; that throughout His nature, He is one and the same, and therefore that He is His Deitas, His vita, and whatever else may be predicated of Him. Next it is shown (Qu. iv.) that God is perfect; that in Him are the perfectiones of all things, since whatever there may be of perfection in an effect, should be found in the effective cause; and as God is self-existent being, He must contain the whole perfection of being in Himself (totam perfectionem essendi in se). Next, that God is the good (bonum) and the summum bonum; He is infinite; He is in all things (Qu. viii. Art. 1) not as a part of their essence, but as accidens, and as the doer is in his deeds; and not only in their beginning, but so long as they exist; He acts upon everything immediately, and nothing is distant from Him; God is everywhere: as the soul is altogether in every part of the body, so God entire is in all things and in each. God is in all things created by Him as the working cause; but He is in the rational creature, through grace; as the object of action is in the actor, as the known is in the knower, and the desired in the wishful. God is immutable (Qu. ix.); for as final actuality (actus purus), with no admixture of potentiality, He cannot change; nor can He be moved; since His infinitude comprehends the plenitude of all perfection, there is nothing that He can acquire, and no whither for Him to extend. God is eternal (Qu. x.); for him there is no beginning, nor any succession of time; but an interminable now, an all at once (tota simul), which is the essence of eternity, as distinguished from the successiveness of even infinite time. And God is One (Qu. xi.). “One does not add anything to being, save negation of division. For One signifies nothing else than undivided being (ens indivisum). And from this it follows that One is convertible with being.” That God is One, is proved by His simplicitas; by the infiniteness of His perfection; and by the oneness of the world.
“After a consideration,” now says Thomas, “of those matters which pertain to the divine substance, we may consider those which pertain to its action (operatio). And because certain kinds of action remain in the doer, while others pass out into external effect, we first treat of knowledge and will (for knowing is in the knower and willing in him who wills); and then of God’s power, which is regarded as the source of the divine action passing out into external effect. Then, since knowing is a kind of living, after considering the divine knowledge, the divine life will be considered. And because knowledge is of the true, there will be need to consider truth and falsity. Again since every cognition is in the knower, the rationes (types, essential natures) of things as they are in God the Knower (Deo cognoscente) are called ideas (ideae); and a consideration of these will be joined to the consideration of knowledge.”[594]
Thus clearly laying out his topic, Thomas begins his discussion of God’s knowledge (scientia Dei); of the modes in which God knows and the knowledge which He has. In God is the most perfect knowledge. God knows Himself through Himself; in Him knowledge and Knower (intellectum and intellectus) are the same.[595] He perfectly comprehends Himself; for He knows Himself so far as He is knowable; and He is absolutely knowable being utter reality (actus purus). Likewise He knows things other than Himself. For He knows Himself perfectly, which implies a knowledge of those things to which His power (virtus) extends. Moreover, He knows all things in their special natures and distinctions from each other: for the perfection, or perfected actuality, of everything is contained in Him; and therefore God in Himself is able to know all things perfectly, and the special nature of everything exists through some manner of participation in the divine perfection. God knows all things in one, to wit, Himself; and not successively, or by means of discursive reasoning. “God’s knowledge is the cause of things. It stands to all created beings as the knowledge of the artificer to the things he makes. God causes things through His knowledge, since His being is His knowing (cum suum esse sit suum intelligere).” His knowledge causes things when it has the will joined with it, and, in so far as it is the cause of things, is called scientia approbationis. God knows things which are not actually (actu). Whatever has been or will be, He knows by the knowledge of sight (scientia visionis, which by implication is equivalent to scientia approbationis). For God’s knowing, which is His being, is measured by eternity; and eternity includes all time, as present, and without succession; so the present vision (intuitus) of God embraces all time and all things existing at any time, as if present. As for whatever is in the power of God or creature, but which never has been or will be, God knows it not as in vision, but simply knows it.
God also knows evil.
“Whoever knows anything perfectly should know whatever might happen to it. There are some good things to which it may happen to be corrupted through evils: wherefore God would not know the good perfectly, unless He also knew the evil. Everything is knowable so far as it is; but the being (esse) of evil is the privation of good: hence inasmuch as God knows good, He knows evil, as darkness is known through light.”