Every virtuous act (for example, an act of generosity) involves personal risk. A coward, a person without courage, won't take the risk, and thus won't be generous. So you could say that courage is the prerequisite virtue for every other virtue. It is not the greatest of virtues, but the most necessary. - Summary in English of Comte-Sponville, Diccionario filosófico, 108. It's understandable when a good person gives in to cowardice. But a person who is always a coward cannot be a virtuous person, because virtue depends on courage.