Now, as to the _differentia_, which brings us to a more specific statement of the doctrine of the _Mean_. The specific excellence of virtue is to be got at from quantity in the abstract, from which we derive the conceptions of more, less, and equal; or excess, defect, and mean; the equal being the mean between excess and defect. But in the case of moral actions, the arithmetical mean may not hold (for example, six between two and ten); it must be a mean relative to the individual; Milo must have more food than a novice in the training school. In the arts, we call a work perfect, when anything either added or taken away would spoil it. Now, virtue, which, like Nature, is better and more exact than any art, has for its subject-matter, passions and actions; all which are wrong either in defect or in excess. Virtue aims at the mean between them, or the maximum of Good: which implies a correct estimation of all the circumstances of the act,--when we ought to do it--under what conditions--towards whom--for what purpose--in what manner, &c. This is the praise-worthy mean, which virtue aspires to. We may err in many ways (for evil, as the Pythagoreans said, is of the nature of the Infinite, good of the Finite), but we can do right only in one way; so much easier is the path of error. Combining then this _differentia_ with the _genus_, as above established, the complete definition is given thus--'Virtue is an acquirement or fixed state, tending by deliberate purpose (genus), towards a mean relative to us (difference).' To which is added the following all-important qualification, 'determined by reason [Greek: logos], and as the _judicious man_ [Greek: ho Phronimos] would determine.' Such is the doctrine of the Mean, which combines the practical matter-of-fact quality of moderation, recognized by all sages, with a high and abstract conception, starting from the Pythagorean remark quoted by Aristotle, 'the Infinite, or Indefinite, is evil, the Finite or the Definite is good,' and re-appearing in Plato as 'conformity to measure' [Greek: metriotaes], by which he (Plato) proposes to discriminate between good and evil. The concluding qualification of virtue--'a rational determination, according to the ideal judicious man'--is an attempt to assign a standard or authority for what is the proper 'Mean;' an authority purely ideal or imaginary; the actual authority being always, rightly or wrongly, the society of the time.