Full Idea
Virtue (as the worthiness to be happy) is the supreme condition of whatever appears to us to be desirable and thus of all our pursuit of happiness and, consequently, the supreme good.
Gist of Idea
Virtue is the supreme state of our pursuit of happiness, and so is supreme good
Source
Immanuel Kant (Critique of Practical Reason [1788], I.II.II)
Book Reference
Kant,Immanuel: 'Critique of Practical Reason (Third edition)', ed/tr. Beck,Lewis White [Library of Liberal Arts 1993], p.116
A Reaction
Thus Kant can claim to be a virtue theorist, but giving us a very different account of how virtue arises. He emphasises elsewhere (Idea 6197) that the supreme good must be in the will, not in the outcome. 'Virtue' is here a rather thin concept.
Related Idea
Idea 6197 Morality involves duty and respect for law, not love of the outcome [Kant]