The principal act of prudence is the practical executive command of
right reason, and the following virtues come within its orbit; good
counsel, sound judgment when the ordinary rules of conduct are
concerned, and a flair for dealing with exceptional cases.

As regards justice, its classical type renders what is due between
equals, but other virtues come under the general heading of justice.
Some render what is owing to another, but not as to an equal. Others
deal with a situation where both parties are equal, yet the due or
debt, though demanded by decency, cannot be enforced by law, and so
is not an affair of strict justice. In the first category of these
phases of justice comes religion, which offers our service and
worship to God, then piety and patriotism, which render our duty to
parents and country, then observance, which shows reverence to
superiors, and obedience to their commands. In the second category
come gratitude for past favors, and vindication when injury has been
done; also truthfulness, without which social decency is impossible,
liberality in spending money, and friendliness or social good
manners.

Meditate on these and try to find a way of explaining this.

The respective parts of fortitude, on the attacking side, are
confidence, carried out with magnificence, which reckons not the
cost, and magnanimity, which does not shrink from glory. On the
defensive side is patience, which keeps an unconquered spirit, and
can be protracted into perseverance.

Finally the subordinated kinds of temperance are continence, which
resists lustfulness and evil desires concerned with touch, clemency
which tempers punishment, meekness that tempers anger, modesty in our
deportment, including disciplined study, reasonable recreation and
good taste in clothes.

Aquinas concluded with the necessity of infused moral virtues from
the principle of consistency between the natural and supernatural. It
is obvious, he reasoned, that a person in the state of grace performs
actions of other virtues than just the theological, that is, of
justice, prudence, temperance and fortitude. These actions are
essentially supernatural, and therefore require, besides the state of
grace, moral habits that are equally supernatural. Otherwise we
should postulate an imbalance in the moral order, since God's
ordinary providence uses secondary causes of the same kind as the
effects produced. If we are to have truly supernatural acts of
justice and chastity, for example, we should have infused
supernatural virtues that proximately bring these actions about. In
the last analysis, there must be infused moral virtues, in addition
to the theological, because of faith in the person justified. A moral
virtue, by definition, avoids extremes. It does not offend against
right reason by excess or by defect. But once the faith is had, there
is not question of limiting the practice of moral virtue by reason
alone. Faith sublimates reason as the standard of moderation; and
just as prior to faith there are acquired virtues commensurate with
reason to assist the natural mind and will in the performance of
morally good acts, so with the advent of faith there should be
corresponding supernatural virtues commensurate with the light of
faith to assist the elevated human faculties in the performance of
supernaturally good actions in the moral order.

A slight problem arises from the fact that the infused virtues are
necessarily spiritual and the infusion must directly take place in
the mind and will, in spite of the fact that two of the virtues,
temperance and fortitude, involve the sense appetite. One explanation
is to have the virtues immediately enter the spiritual faculties, and
these in turn affect the less powers as called upon for moral action.

Here, if anywhere, the familiar dictum that "grace does not destroy
but builds upon nature" is eminently true. All that we say about
these virtues as naturally acquired qualities holds good for the
infused, but much more. With reason enlightened by faith, the scope
of virtuous operation is extended to immeasurably wider horizons. By
the same token faith furnishes motives of which reason would never
conceive, and theological charity offers inspiration that surpasses
anything found in nature.