Nicomachean Ethics by Aristóteles — Read

There are, as we said, three classes of disposition, viz. two kinds of vice, one marked by excess, the other by deficiency, and one kind of virtue, the observance of the mean. Now, each is in a way opposed to each, for the extreme dispositions are opposed both to the mean or moderate disposition and to one another, while the moderate disposition is opposed to both the extremes. Just as a quantity which is equal to a given quantity is also greater when compared with a less, and less when compared with a greater quantity, so the mean or moderate dispositions exceed as compared with the defective dispositions, and fall short as compared with the excessive dispositions, both in feeling and in action; e.g. the courageous man seems foolhardy as compared with the coward, and cowardly as compared with the foolhardy; and similarly the temperate man appears profligate in comparison with the insensible, and insensible in comparison with the profligate man; and the liberal man appears prodigal by the side of the illiberal man, and illiberal by the side of the prodigal man.

And so the extreme characters try to displace the mean or moderate character, and each represents him as falling into the opposite extreme, the coward calling the courageous man foolhardy, the foolhardy calling him coward, and so on in other cases.