Summa Theologiae Moralis, vol. I: De Principiis

S. Th. II-II, qq. 8 and 9.

730. The gift of understanding, under the interior instinct of the Holy Spirit, serves to penetrate with supernatural light those things which we cannot penetrate by natural light, and which stand in faith as principles from which other things are deduced (q. 8, a. 1).

Moreover, during the state of the way we are not able to penetrate these things in themselves; but we penetrate that other evident truths are not opposed to them (a. 2).

This happens according to a triple grade.

"The first grade of the gift of understanding is that by it man knows that he must hold to the truths of faith according to what is necessary for salvation, considering some reason of the Christian faith on account of which he knows that he must believe. For the Holy Spirit shows to everyone who has grace at least some reason of faith, on account of which he sees that what is proposed to him by faith comes from God..."

The second grade of the gift of understanding is to speculate subtly all or at least the chief truths of faith: and thus to be established all the more firmly in the truths of faith, the more diligently one considers the foundations of faith, so that one may abundantly marvel that God has deigned to reveal the faith so copiously and evidently... For the more profoundly the things which God has revealed are examined, the more they shine forth as the most certain and the most worthy of contemplation.

The third grade belongs to being able to consider with the purest gaze the proper reasons and foundations of each article of faith, and so to be able to speculate each truth of faith separately with the most subtle and most certain eye of mind, contemplating, namely, that it is reasonable to be believed, and considering the basis on which it rests... — both on account of the evangelical testimonies and apostolic documents, and on account of the most beautiful persuasions drawn from the natures of things. Moreover, contemplating the reasons of faith regarding the incarnation of the Son of God, the oracles of the prophets, the testimonies of the apostles, the reasonable considerations by which it is proved that this was fitting, and thus considering about each article or part of faith its proper foundations, and how they assert almost nothing about Christ which is not shown to have been predicted by the holy prophets...¹ "

To this gift corresponds the sixth beatitude: Blessed are the pure in heart, for they shall see God. For the gift of understanding purifies the mind from the phantasms and errors by which we would ill-receive or ill-understand those things which are proposed about God; but the more we are purified from these, the better we see God, insofar as in this life it is possible to see Him in a mirror and in an enigma.

"For there is a twofold purity: one preliminary and dispositive for the vision of God, which is the purification of the affections from disordered affections; and this purity of heart is produced through the virtues and gifts which belong to the appetitive power. The other purity of heart is, as it were, completive with respect to the vision of God; and it consists in the mind being purified from the phantasms and errors by which it is impeded from the contemplation of those things which are seen in God, even as regards the intellective cognition by which the mind is borne to those things which are seen in God. And the first purity corresponds to the virtue of temperance; but the second corresponds to the gift of understanding."

To the gift of understanding correspond the fruits of the Holy Spirit, faith — that is, the certitude of faith which produces delight in the mind; in the will, however, the fruit joy corresponds (a. 8).

731. The gift of knowledge, under the interior instinct of the Holy Spirit, serves to judge rightly and certainly according to the truth of faith about human and created things, discerning which of these are to be believed and which are not to be believed (q. 9, a. 1 and 2).

"The gift of knowledge has three grades.

The first consists in this, that man looks upon all created things, knows that they are fallible and vain according to their divine nature, understands that they are not to be loved for their own sake, nor to be sought as the ultimate end, and clings to them less than to God; and this grade of the gift of knowledge is required for salvation, and is held to be common to all having charity..."

To the second grade of this knowledge we ought to progress, namely, that about each created thing, singly and through its proper reasons, we may know that affection is not to be fixed in it, nor is one to be tied to it as to a final good, but in them one neither intends nor uses them more nor less than is required for the intermission of the soul from those things which are directed to the ultimate end... [S. Th. II-II, q. 9, a. 4].

The third grade, finally, of the gift of knowledge, is to be so practiced, experienced, and perfect in those things which concern the active life, that in every doubtful event and perplexing case one may know most truly, most promptly, and most wholesomely how to judge, to elicit the causes of sins, to set forth the reasons for a negligent and sluggish life, and to know how to correct these and apply the appropriate remedy, to induce contempt for temporal things, and to attend to the most serious and tireless pursuit of spiritual progress².

To the gift of knowledge corresponds the third beatitude: Blessed are those who mourn, for they shall be comforted. For he who judges rightly about creatures does not find in them a perfect good, but rather mourns over them, and orders them to the divine good; from which consolation follows (a. 4).

732. Observations. — 1. To revealed truths we simply adhere by faith; by the gift of understanding we penetrate them.

2. The gift of knowledge differs from the gift of understanding: this proceeds by way of simple apprehension, "so that the things which are of faith may be penetrated or grasped by the intellect"; that proceeds by way of judgment, "so that man may have a right judgment about them and may esteem that he must hold to them and recede from their opposites" [S. Th. II-II, q. 9, a. 3].

3. These gifts, like faith, are primarily speculative in themselves, but secondarily practical (a. 3). Thus S. Thomas, in the present, retracts what he had written to the contrary in I-II, q. 68, a. 4 (a. 6).

4. Two vices are opposed to the gift of understanding: blindness of mind, and dullness of sense. The latter "imports a certain debility (or obtusion) of mind about the consideration of spiritual goods; but blindness of mind imports the complete privation of the knowledge of them" (q. 15, a. 1). Dullness arises from gluttony; blindness, from lust.

To the gift of knowledge, ignorance is directly opposed.