Full Idea
Excessive and insufficient exercise or food destroy one's strength or health, whereas the right quantity produces, increases and preserves them. It is the same with temperance, courage and the other virtues.
Gist of Idea
Excess and deficiency are bad for virtue, just as they are for bodily health
Source
Aristotle (Nicomachean Ethics [c.334 BCE], 1104a15)
Book Reference
Aristotle: 'Ethics (Nicomachean)', ed/tr. ThomsonJ A K/TredennickH [Penguin 1976], p.94
A Reaction
An example of Aristotle's philosophy originating in his biological background. This appears to be true of health, but he notes exceptions in morality. Adultery has no mean. In health a middle way is needed, but in morality it is what is 'appropriate'.