Kant on Virtue (or character)

The human being who is conscious of having character in his way of thinking does not have it by nature; he must always have acquired it. One may also assume that the grounding of character is like a kind of rebirth, a certain solemnity of making a vow to oneself; which makes the resolution and the moment when this transformation took place unforgettable to him/ like the beginning of a new epoch. - Education, examples, and teaching generally cannot bring about this firmness and persistence in principles gradually, but only, as it were, by an explosion which happens one time as a result of weariness at the unstable condition of instinct. Perhaps there are only a few who have attempted this revolution before the age of thirty, and fewer still who have firmly established it before they are forty. - Wanting to become a better human being in a fragmentary way is a futile endeavor, since one impression dies out while one works on another; the grounding of character, however, is absolute unity of the inner principle of conduct as such. - It is also said that poets have no character, for example, they would rather insult their best friends than give up a witty inspiration; or that character is not to be sought at all among courtiers, who must put up with all fashions; 6 and that with clergymen, who court the Lord of Heaven as well as the lords of the earth in one and the same pitch/firmness of character is in a troublesome condition; and, accordingly, it probably is and will remain only a pious wish that they have inner (moral)* character. But perhaps the philosophers are to blame for this, because they have never yet isolated this concept and placed it in a sufficiently bright light, and have sought to present virtue only in fragments but have never tried to present it whole, in its beautiful form, and to make it interesting for all human beings.

from Anthropology from a Pragmatic Point of View in Anthropology, History, and Education (p.392)