Virtue ... is a mean between two vices, that which depends on excess and that which depends on defect; and again it is a mean because the vices respectively fall short of or exceed what is right in both passions and actions, while virtue both finds and chooses that which is intermediate. Hence in respect of its substance and the definition which states its essence virtue is a mean, with regard to what is best and right an extreme.
Monks, these two extremes ought not to be practiced by one who has gone forth from the household life. What are the two? There is addiction to indulgence of sense-pleasures, which is low, coarse, the way of ordinary people, unworthy, and unprofitable; and there is addiction to self-mortification, which is painful, unworthy, and unprofitable. Avoiding both these extremes, the Tathagata has realized the Middle Path; it gives vision, gives knowledge, and leads to calm, to insight, to enlightenment and to Nibbana. And what is that Middle Path realized by the Tathagata? ... It is the Noble Eightfold Path, and nothing else, namely: right understanding, right thought, right speech, right action, right livelihood, right effort, right mindfulness and right concentration.
Those words, "temperate and moderate", are words either of political cowardice, or of cunning, or seduction. A thing, moderately good is not so good as it ought to be. Moderation in temper, is always a virtue; but moderation in principle, is a species of vice.
Thomas Paine, letter to the addressers on the late proclamation against seditious writings; in Moncure D. Conway, ed., The Writings of Thomas Paine (1895), vol. 3, p. 94–95.