Book Three — Providence, Chapter 154 — Summa Contra Gentiles
[1] Since man can only know the things that he does not see himself by taking them from another who does see them, and since faith is among the things we do not see, the knowledge of the objects of faith must be handed on by one who sees them himself. Now, this one is God, Who perfectly comprehends Himself, and naturally sees His essence. Indeed, we get faith from God. So, the things that we hold by faith must come to us from God. But, since the things that come from God are enacted in a definite order, as we showed above, a certain order had to be observed in the manifestation of the objects of faith. That is to say, some persons had to receive them directly from God, then others from them, and so on in an orderly way down to the lowest persons.
[2] Now, wherever there is an order among things, it is necessary that, the nearer one thing is to the first principle, the stronger it must be. This is apparent in the order of divine manifestation. For invisible things whose vision is beatifying, and to which faith applies, are first revealed by God to the blessed angels through open vision, as is clear from our previous statements.
[3] In turn, by the intermediary ministry of the angels they are manifested to certain men; not, of course, through open vision, but through a kind of certitude resulting from divine revelation.
[4] This revelation, then, is accomplished by means of a certain interior and intelligible light, elevating the mind to the perception of things that the understanding cannot reach by its natural light. For, just as the understanding by its natural light is made certain concerning things that it knows by that light (for instance, concerning first principles), so also does it acquire certitude concerning things which it apprehends by supernatural light. Now, this latter certitude is needed so that the things that are grasped by divine revelation may be offered to others, for we cannot present things to others with assurance if we have not certain knowledge of them. Now, accompanying this light that we have mentioned, which illumines the mind from within, there are at times in divine revelation other external or internal aids to knowledge; for instance, a spoken message, or something heard by the external senses which is produced by divine power, or something perceived internally through imagination due to God’s action, or also some things produced by God that are seen by bodily vision, or that are internally pictured in the imagination. From these presentations, by the light internally impressed on the mind, man receives a knowledge of divine things. Consequently, without the interior light, these aids do not suffice for a knowledge of divine things, but the interior light does suffice without them.
[5] However, this revelation of the invisible things of God belongs to wisdom, which is properly the knowledge of divine things. ‘nus, it is said in Wisdom (7:27-28) that the wisdom of God “conveys herself through nations into holy souls… for God loves no one but him who dwells with wisdom.” And again in Sirach (15:5) it is said: “the Lord has filled him with the spirit of wisdom and understanding.”
[6] But, since “the invisible things of God… are clearly seen, being understood by the things that are made,” not only divine things are revealed to men by divine grace, but also some created things, and this seems to pertain to knowledge. Hence, it is said in Wisdom (7:17): “For He has given me the true knowledge of the things that are: to know the disposition of the whole world, and the virtues of the elements.” And in 2 Chronicles (1:12) the Lord said to Solomon: “Knowledge and wisdom are granted to you.”
[7] But the things that man knows he cannot properly convey to the knowledge of another man, except by speech. So, since those who receive a revelation from God, according to the divinely established order, should instruct others, it was necessary for them also to be given the grace of speech, in keeping with what the benefit of those who were to be instructed demanded. Hence, it is said in Isaiah (50:4): “The Lord hath given me a learned tongue, that I should know how to uphold by word him that is weary.” And the Lord says to the disciples, in Luke (21:15): “I will give you a mouth and wisdom, which all your adversaries shall not be able to resist and gainsay.” And also for this reason, when it was necessary for the truth of the faith to be preached by a few men to different peoples, some were divinely instructed to “speak with divers tongues,” as is said in Acts (2:4): “They were all filled with the Holy Spirit: and they began to speak with divers tongues, according as the Holy Spirit gave them to speak.”
[8] But because oral teaching that is offered requires confirmation so that it may be accepted, unless it be evident in itself, and because things that are of faith are not evident to human reason, it was necessary for some means to be provided whereby the words of the preachers of the faith might be confirmed. Now, they could not be confirmed by any rational principles in the way of demonstration, since the objects of faith surpass reason. So, it was necessary for the oral teaching of the preachers to be confirmed by certain signs, whereby it might be plainly shown that this oral teaching came from God; so, the preachers did such things as healing the sick, and the performance of other difficult deeds, which only God could do. Hence, the Lord, sending forth His disciples to preach, said in Matthew (10:8): “Heal the sick, raise the dead, cleanse the lepers, cast out devils.” And it is said at the end of Mark (16:20): “But they going forth preached everywhere: the Lord working withal, and confirming the word with signs that followed.”