Whether it is expedient to grieve for sin continually?

Objections

Objection 1 : It would seem that it is not expedient to grieve for sin continually. For it is sometimes expedient to rejoice, as is evident from Phil. 4:4, where the gloss on the words, "Rejoice in the Lord always," says that "it is necessary to rejoice." Now it is not possible to rejoice and grieve at the same time. Therefore it is not expedient to grieve for sin continually.
Objection 2 : Further, that which, in itself, is an evil and a thing to be avoided should not be taken upon oneself, except in so far as it is necessary as a remedy against something, as in the case of burning or cutting a wound. Now sorrow is in itself an evil; wherefore it is written (Ecclus. 30:24): "Drive away sadness far from thee," and the reason is given (Ecclus. 30:25): "For sadness hath killed many, and there is no profit in it." Moreover the Philosopher says the same (Ethic. vii, 13,14; x, 5). Therefore one should not grieve for sin any longer than suffices for the sin to be blotted out. Now sin is already blotted out after the first sorrow of contrition. Therefore it is not expedient to grieve any longer.
Objection 3 : Further, Bernard says (Serm. xi in Cant.): "Sorrow is a good thing, if it is not continual; for honey should be mingled with wormwood." Therefore it seems that it is inexpedient to grieve continually.