Aristotle, Nicomachean Ethics
H. Rackham, Ed.

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.2. [8]

But¹ not only are the virtues both generated and fostered on the one hand, and destroyed on the other, from and by the same actions, but they will also find their full exercise in the same actions. This is clearly the case with the other more visible qualities, such as bodily strength: for strength is produced by taking much food and undergoing much exertion, while also it is the strong man who will be able to eat most food and endure most exertion. 2. [9] The same holds good with the virtues. We become temperate by abstaining from pleasures, and at the same time we are best able to abstain from pleasures when we have become temperate.