It rarely happens that we break in upon that plan of conduct, which the governing principle prescribes, and which in all our cool hours we had laid down to ourselves as what was most proper for us to pursue, but when prompted by one or other of those two different sets of passions; either by ungovernable ambition and resentment, or by the importunate solicitations of present ease and pleasure. But though these two orders of passions are so apt to mislead us, they are still considered as necessary parts of human nature: the first having been given to defend us against injuries, to assert our rank and dignity in the world, to make us aim at what is noble and honourable, and to make us distinguish those who act in the same manner; the second to provide for the support and necessities of the body. In the strength, acuteness, and perfection of the governing principle was placed the essential virtue of prudence, which, according to Plato, consisted in a just and clear discernment, founded upon general and scientific ideas, of the ends which were proper to be pursued, and of the means which were proper for attaining them. When the first set of passions, those of the irascible part of the soul, had that degree of strength and firmness, which enabled them, under the direction of reason, to despise all dangers in the pursuit of what was honourable and noble; it constituted the virtue of fortitude and magnanimity. This order of passions, according to this system, was of a more generous and noble nature than the other. They were considered upon many occasions as the auxiliaries of reason, to check and restrain the inferior and brutal appetites. We are often angry at ourselves, it was observed, we often become the objects of our own resentment and indignation, when the love of pleasure prompts to do what we disapprove of; and the irascible part of our nature is in this manner called in to assist the rational against the concupiscible. When all those three different parts of our nature were in perfect concord with one another, when neither the irascible nor concupiscible passions ever aimed at any gratification which reason did not approve of, and when reason never commanded any thing, but what these of their own accord were willing to perform; this happy composure, this perfect and complete harmony of soul, constituted that virtue which in their language is expressed by a word which we commonly translate temperance, but which might more properly be translated good temper, or sobriety and moderation of mind.