Thomas Aquinas

“ Virtue is a mean between passions, not by reason of its essence, but on account of its effect; because, to wit, it establishes the mean between passions.
Reply to Objection 2: If by vice we understand a habit of doing evil deeds, it is evident that no passion is a vice. But if vice is taken to mean sin which is a vicious act, nothing hinders a passion from being a vice, or, on the other hand, from concurring in an act of virtue; in so far as a passion is either opposed to reason or in accordance with reason. ”

“ Therefore sorrow is compatible with moral virtue in the same way as the other passions are when moderated by reason.
Their second reason for holding this opinion was that sorrow is about evil present, whereas fear is for evil to come: even as pleasure is about a present good, while desire is for a future good. Now the enjoyment of a good possessed, or the desire to have good that one possesses not, may be consistent with virtue: but depression of the mind resulting from sorrow for a present evil, is altogether contrary to reason: wherefore it is incompatible with virtue. ”

“ For there is an evil which can be present to the virtuous man, as we have just stated; which evil is rejected by reason. Wherefore the sensitive appetite follows reason's rejection by sorrowing for that evil ”

“ On the other hand, virtue sorrows moderately for all that thwarts virtue, no matter how.
Reply to Objection 1: The passage quoted proves that the wise man is not made sorrowful by wisdom. Yet he sorrows for anything that hinders wisdom. Consequently there is no room for sorrow in the blessed, in whom there can be no hindrance to wisdom. ”

“ Consequently the evil which is contrary to this good can be in a wise man, and can cause him moderate sorrow. Again, although a virtuous man can be without grave sin, yet no man is to be found to live without committing slight sins, according to 1 Jn. ”

“ These emotions could not be in a wise or virtuous man if they arose deliberately: while it would be possible for them to be in a wise man, if they arose suddenly: because, in the words of Aulus Gellius [*Noct. Attic. xix, 1] , quoted by Augustine (De Civ. Dei ix, 4) , "it is not in our power to call up the visions of the soul, known as its fancies ”