Reply Obj. 1: Moderate sorrow, that does not cause the mind to wander, can conduce to the acquisition of learning especially in regard to those things by which a man hopes to be freed from sorrow. And thus, "in the tribulation of murmuring," men are more apt to be taught by God.
Reply Obj. 2: Both pleasure and pain, in so far as they draw upon themselves the soul's intention, hinder the reason from the act of consideration, wherefore it is stated in Ethic. vii, 11 that "in the moment of sexual pleasure, a man cannot understand anything." Nevertheless pain attracts the soul's intention more than pleasure does: thus we observe in natural things that the action of a natural body is more intense in regard to its contrary; for instance, hot water is more accessible to the action of cold, and in consequence freezes harder. If therefore pain or sorrow be moderate, it can conduce accidentally to the facility of learning, in so far as it takes away an excess of pleasure. But, of itself, it is a hindrance; and if it be intense, it prevents it altogether.
Reply Obj. 3: External pain arises from hurt done to the body, so that it involves bodily transmutation more than inward sorrow does: and yet the latter is greater in regard to the formal element of pain, which belongs to the soul. Consequently bodily pain is a greater hindrance to contemplation which requires complete repose, than inward sorrow is. Nevertheless if inward sorrow be very intense, it attracts the intention, so that man is unable to learn anything for the first time: wherefore on account of sorrow Gregory interrupted his commentary on Ezechiel (Hom. xxii in Ezechiel). ________________________
SECOND ARTICLE [I-II, Q. 37, Art. 2]
Whether the Effect of Sorrow or Pain Is to Burden the Soul?
Objection 1: It would seem that it is not an effect of sorrow to burden the soul. For the Apostle says (2 Cor. 7:11): "Behold this self-same thing, that you were made sorrowful according to God, how great carefulness it worketh in you: yea, defence, yea indignation," etc. Now carefulness and indignation imply that the soul is uplifted, which is contrary to being depressed. Therefore depression is not an effect of sorrow.
Obj. 2: Further, sorrow is contrary to pleasure. But the effect of pleasure is expansion: the opposite of which is not depression but contraction. Therefore depression should not be reckoned as an effect of sorrow.
Obj. 3: Further, sorrow consumes those who are inflicted therewith, as may be gathered from the words of the Apostle (2 Cor. 2:7): "Lest perhaps such an one be swallowed up with overmuch sorrow." But that which is depressed is not consumed; nay, it is weighed down by something heavy, whereas that which is consumed enters within the consumer. Therefore depression should not be reckoned an effect of sorrow.
On the contrary, Gregory of Nyssa [*Nemesius, De Nat. Hom. xix.] and Damascene (De Fide Orth. ii, 14) speak of "depressing sorrow."
I answer that, The effects of the soul's passions are sometimes named metaphorically, from a likeness to sensible bodies: for the reason that the movements of the animal appetite are like the inclinations of the natural appetite. And in this way fervor is ascribed to love, expansion to pleasure, and depression to sorrow. For a man is said to be depressed, through being hindered in his own movement by some weight. Now it is evident from what has been said above (Q. 23, A. 4; Q. 25, A. 4; Q. 36, A. 1) that sorrow is caused by a present evil: and this evil, from the very fact that it is repugnant to the movement of the will, depresses the soul, inasmuch as it hinders it from enjoying that which it wishes to enjoy. And if the evil which is the cause of sorrow be not so strong as to deprive one of the hope of avoiding it, although the soul be depressed in so far as, for the present, it fails to grasp that which it craves for; yet it retains the movement whereby to repulse that evil. If, on the other hand, the strength of the evil be such as to exclude the hope of evasion, then even the interior movement of the afflicted soul is absolutely hindered, so that it cannot turn aside either this way or that. Sometimes even the external movement of the body is paralyzed, so that a man becomes completely stupefied.