* The common classical formulae of ethics- medio tutissimus ibis; omne mimium vertitur in vitium; est modus in rebus, etc., medium tenuere beati; virtus est medium vitiorum et utrinque reductum- ["You will go most safely in the middle" (Virgil); "Every excess develops into a vice"; "There is a mean in all things, etc." (Horace); "Happy they who steadily pursue a middle course"; "Virtue is the mean between two vices and equally removed from either" (Horace).]- contain a poor sort of wisdom, which has no definite principles; for this mean between two extremes, who will assign it for me? Avarice (as a vice) is not distinguished from frugality (as a virtue) by merely being the lat pushed too far; but has a quite different principle; (maxim), namely placing the end of economy not in the enjoyment of one's means, but in the mere possession of them, renouncing enjoyment; just as the vice of prodigality is not to be sought in the excessive enjoyment of one's means, but in the bad maxim which makes the use of them, without regard to their maintenance, the sole end.
For the same reason, no vice can be defined as an excess in the practice of certain actions beyond what is proper (e.g., Prodigalitas est excessus in consumendis opibus); or, as a less exercise of them than is fitting (Avaritia est defectus, etc.). For since in this way the degree is left quite undefined, and the question whether conduct accords with duty or not, turns wholly on this, such an account is of no use as a definition.
Thirdly. Ethical virtue must not be estimated by the power we attribute to man of fulfilling the law; but, conversely, the moral power must be estimated by the law, which commands categorically; not, therefore, by the empirical knowledge that we have of men as they are, but by the rational knowledge how, according to the ideas of humanity, they ought to be. These three maxims of the scientific treatment of ethics are opposed to the older apophthegms: