The integral parts of Prudence are those parts of the virtue which are necessary for the virtue to be exercised perfectly. Analogous to the foundation, walls and roof of a house, without them the house (one’s action) will be shaky, if not dilapidated.
They, therefore, concern the things the prudent person must know, in order to judge rightly, as well as the things to be concerned with in judging and putting the decision into action.
The exercise of the virtue is not perfect without all of Prudence’s integral parts. An imperfect act of virtue, therefore, is imprudent, even if the moral object (the thing done) and the intention of the will is good.