Saint Thomas declared, is the fourth and final cardinal virtue. While fortitude is concerned with the restraint of fear so that we can act, temperance is the restraint of our desires or passions. Food, drink, and sex are all necessary for our survival, individually and as a species; yet a disordered desire for any of these goods can have disastrous consequences, physical and moral.
Temperance is the virtue that attempts to keep us from excess, and, as such, requires the balancing of legitimate goods against our inordinate desire for them. Our legitimate use of such goods may be different at different times; temperance is the "golden mean" that helps us determine how far we can act on our desires.