If every tool, when ordered, or even of its own accord, could do the work that befits it... then there would be no need either of apprentices for the master workers or of slaves for the lords.
AristotleFor both excessive and insufficient exercise destroy one's strength, and both eating and drinking too much or too little destroy health, whereas the right quantity produces, increases and preserves it. So it is the same with temperance, courage and the other virtues. This much then, is clear: in all our conduct it is the mean that is to be commended.
Aristotle