3. Plato compares the rational soul in man to a charioteer, driving two horses: one horse representing the concupiscible, the other the irascible part of the sensitive appetite. He draws a vivid picture of the resistance of the concupiscible part against reason, how madly it rushes after lawless pleasure, and how it is only kept in restraint by main force again and again applied, till gradually it grows submissive. This submissiveness, gradually acquired, is the virtue of temperance. Clearly the habit dwells in the appetite, not in reason: in the horse, not in the charioteer. It is that habitual state, which in a horse we call _being broken in_. The concupiscible appetite is _broken in_ to reason by temperance residing within it. Plato lavishes all evil names on the steed that represents the concupiscible part. But the irascible part, the other steed, has its own fault, and that fault twofold, sometimes of over-venturesomeness, sometimes of shying and turning tail. The habit engendered, in the irascible part, of being neither over-venturesome nor over-timorous, but going by reason, is termed fortitude. [Footnote 6] [Footnote 6: It will help an Englishman to understand Plato's comparison, if instead of _concupiscible part_ and _irascible part_, we call the one steed Passion and the other Pluck. Pluck fails, and Passion runs to excess, till Pluck is formed to fortitude, and Passion to temperance.] 4. As the will is the rational appetite, the proper object of which is rational good, it does not need to be prompted by any habit to embrace rational good in what concerns only the inward administration of the agent's own self. There is no difficulty in that department, provided the sensitive appetite be kept in hand by fortitude and temperance. But where there is question of external relations with other men, it is not enough that the sensitive appetite be regulated, but a third virtue is necessary, the habit of justice, to be planted in the will, which would otherwise be too weak to attend steadily to points, not of the agent's own good merely, but of the good of other men. 5. Thus we have the four cardinal virtues: prudence, a habit of the intellect; temperance, a habit of the concupiscible appetite; fortitude, a habit of the irascible appetite; and justice, a habit of the will. Temperance and Fortitude in the Home Department; Justice for Foreign Affairs; with Prudence for Premier. Or, to use another comparison, borrowed from Plato, prudence is the health of the soul, temperance its beauty, fortitude its strength, and justice its wealth. _Readings_.--St. Thos., 1a 2æ, q. 61, art. 2, in corp.; _ib_., q. 56, art. 4, in corp., ad 1-3; _ib_., q. 56, art. 6, in corp., ad 1, 3; _ib_., q. 59, art. 4, in corp., ad 2; Plato, _Laws_, 631 B, C. SECTION VI.--_Of Prudence_.