Full Idea
Will is a kind of causality belonging to living beings so far as they are rational. Freedom would then be the property this causality has of being able to work independently of determination by alien causes.
Gist of Idea
Free will is a kind of causality which works independently of other causes
Source
Immanuel Kant (Groundwork of the Metaphysic of Morals [1785], 446.97)
Book Reference
Kant,Immanuel: 'The Moral Law (Groundwork of Morals)', ed/tr. Paton,H.J. [Hutchinson 1948], p.107