The harm principle is articulate most clearly in John Stuart Mill's On Liberty, though it is also articulated in John Locke's Second Treatise of Government and in the work of Wilhelm von Humboldt, to whom Mill is obliged and discusses at length. Mill argues that the sole purpose of law should be to stop people from harming others. Conversely, Mill concludes that government should not forcibly prevent people from engaging in victimless crimes such as gambling, drug usage, and prostitution.