If we restrict the question to acquired virtues, the answer cannot be doubtful. Souls in purgatory can grow in virtue by repetition of natural acts. On earth these virtues, justice, say, or fortitude, grow even in the state of mortal sin, wherein man cannot merit. Further, defective habitudes, the "remains of sin," disappear step by step. They are replaced by acquired virtues. This seems reasonable, above all for such souls as have entered purgatory only by absolution at the moment of death, souls which before, we may say, had acquired no virtue. Acquired virtue, we have seen, prepares for infused virtue, as finger agility subserves the art of the musician. Hence acquired virtues can grow in purgatory, at least those which are in the faculties purely spiritual, as, for instance, prudence and justice. But virtues which involve sense powers, chastity, say, cannot thus grow.
