The notion of private property is endemically problematic and controversial. Although the notion has many defenders its critics have all the best lines: we know, of course, that the institution of private property was denounced as theft and attacked as the product of exploitation and class antagonism. More recently, the notion has been regarded as nothing more than a myth and, in a slight variation on Proudhon's refrain, dismissed as a form of fraud. As if this were not bad enough, it appears that even the thinkers of classical antiquity had severe reservations about the notion although, unusually, their worries were expressed without recourse to pithy rhetoric. Does the notion of private property have any conceptual or normative advantages? Ought we to abandon it altogether? In this essay we offer a negative answer to the first and an affirmative answer to the second question.