Full Idea
By liberty we can only mean a power of acting or not acting according to the determinations of the will, …which is universally allowed to everyone who is not a prisoner and in chains.
Gist of Idea
Liberty is merely acting according to the will, which anyone can do if they are not in chains
Source
David Hume (Enquiry Conc Human Understanding [1748], VIII.I.73)
Book Reference
Hume,David: 'Enquiries Conc. Human Understanding, Morals', ed/tr. Selby-Bigge/Nidditch [OUP 1975], p.95