Full Idea
Our virtues are voluntary, because we ourselves are in a sense partly responsible for our dispositions.
Gist of Idea
We are partly responsible for our own dispositions and virtues
Source
Aristotle (Nicomachean Ethics [c.334 BCE], 1114b21)
Book Reference
Aristotle: 'Ethics (Nicomachean)', ed/tr. ThomsonJ A K/TredennickH [Penguin 1976], p.126
A Reaction
This seems half way to what we would now call existentialism. See Aristotle's other comments on natural virtue. The opposing view is Heraclitus's remark that "character is fate".