Full Idea
So far as his power reaches, of acting or not acting, by the determination of his own thought preferring either, so far is a man free. ..We can scarcely imagine any being freer, than to be able to do what he wills.
Gist of Idea
A man is free insofar as he can act according to his own preferences
Source
John Locke (Essay Conc Human Understanding (2nd Ed) [1694], 2.21.21)
Book Reference
Locke,John: 'Essay Concerning Human Understanding', ed/tr. Nidditch,P.H. [OUP 1979], p.244
A Reaction
It take this approach, which Hume echoes, to be ducking the metaphysical problem, of where the act of willing originates. Locke goes on to admit this.