Obj. 3:  Further, the end corresponds to the beginning.  But man’s Happiness has a beginning, since man was not always happy.  Therefore it seems that it has an end.

On the contrary, It is written (Matt. 25:46) of the righteous that “they shall go . . . into life everlasting,” which, as above stated (A. 2), is the Happiness of the saints.  Now what is eternal ceases not.  Therefore Happiness cannot be lost.

I answer that, If we speak of imperfect happiness, such as can be had in this life, in this sense it can be lost.  This is clear of contemplative happiness, which is lost either by forgetfulness, for instance, when knowledge is lost through sickness; or again by certain occupations, whereby a man is altogether withdrawn from contemplation.

This is also clear of active happiness:  since man’s will can be changed so as to fall to vice from the virtue, in whose act that happiness principally consists.  If, however, the virtue remain unimpaired, outward changes can indeed disturb such like happiness, in so far as they hinder many acts of virtue; but they cannot take it away altogether because there still remains an act of virtue, whereby man bears these trials in a praiseworthy manner.  And since the happiness of this life can be lost, a circumstance that appears to be contrary to the nature of happiness, therefore did the Philosopher state (Ethic. i, 10) that some are happy in this life, not simply, but “as men,” whose nature is subject to change.

But if we speak of that perfect Happiness which we await after this life, it must be observed that Origen (Peri Archon. ii, 3), following the error of certain Platonists, held that man can become unhappy after the final Happiness.

This, however, is evidently false, for two reasons.  First, from the general notion of happiness.  For since happiness is the “perfect and sufficient good,” it must needs set man’s desire at rest and exclude every evil.  Now man naturally desires to hold to the good that he has, and to have the surety of his holding:  else he must of necessity be troubled with the fear of losing it, or with the sorrow of knowing that he will lose it.  Therefore it is necessary for true Happiness that man have the assured opinion of never losing the good that he possesses.  If this opinion be true, it follows that he never will lose happiness:  but if it be false, it is in itself an evil that he should have a false opinion:  because the false is the evil of the intellect, just as the true is its good, as stated in Ethic. vi, 2.  Consequently he will no longer be truly happy, if evil be in him.