Aristotle, Nicomachean Ethics
H. Rackham, Ed.

[7] The same therefore is true of Temperance, Courage, and the other virtues. The man who runs away from everything in fear and never endures anything becomes a coward; the man who fears nothing whatsoever but encounters everything becomes rash. Similarly he that indulges in every pleasure and refrains from none turns out a profligate, and he that shuns all pleasure, as boorish persons do, becomes what may be called insensible. Thus Temperance and Courage are destroyed by excess and deficiency, and preserved by the observance of the mean.