These conflicting tendencies are usually modifiable by reason, and may become in the temperate man completely obedient to reason.

There remains Reason--the highest and sovereign portion of the soul.

Human excellence [Greek: aretae] or virtue, is either of the Appetitive part,--moral [Greek: aethikae] virtue; or of the Reason--intellectual [Greek: dianoaetikae] virtue.

Liberality and temperance are Moral virtues; philosophy, intelligence, and wisdom, Intellectual (XIII.).
Such is an outline of the First Book, having for its subject the Chief Good, the Supreme End of man.
Book Second embraces the consideration of points relative to the Moral Virtues; it also commences Aristotle's celebrated definition and classification of the virtues or excellencies.
Whereas intellectual excellence is chiefly generated and improved by teaching, moral excellence is a result of habit [Greek: ethos]; whence its name (Ethical).

Hence we may see that moral excellence is no inherent part of our nature: if it were, it could not be reversed by habit--any more than a stone can acquire from any number of repetitions the habit of moving upward, or fire the habit of moving downward.