Negative liberty is freedom from interference by other people. Negative liberty is primarily concerned with freedom from external restraint and contrasts with positive liberty (the possession of the power and resources to fulfil one's own potential). According to Thomas Hobbes, "a free man is he that in those things which by his strength and wit he is able to do is not hindered to do what he hath the will to do" (Leviathan, Part 2, Ch. XXI; thus alluding to liberty in its negative sense).