"Two Concepts of Liberty" was the inaugural lecture delivered by the liberal philosopher Isaiah Berlin before the University of Oxford on 31 October 1958. It was subsequently published as a 57-page pamphlet by Oxford at the Clarendon Press. It also appears in the collection of Berlin's papers entitled Four Essays on Liberty (1969) and was more recently reissued in a collection entitled simply Liberty (2002). The essay, with its analytical approach to the definition of political concepts, re-introduced the study of political philosophy to the methods of analytic philosophy. It is also one of Berlin's first expressions of his ethical ontology of value-pluralism. Berlin defined negative liberty (as the term "liberty" was used by Thomas Hobbes) as the absence of coercion or interference with agents' possible private actions, by an exterior social-body. He also defined it as a comparatively recent political ideal, which re-emerged in the late 17th century, after its slow and inarticulate birth in the Ancient doctrines of Antiphon the Sophist, the Cyrenaic discipleship, and of Otanes after the death of pseudo-Smerdis. In an introduction to the essay, Berlin writes: "As for Otanes, he wished neither to rule nor to be ruled—the exact opposite of Aristotle's notion of true civic liberty. ... [This ideal] remains isolated and, until Epicurus, undeveloped ... the notion had not explicitly emerged". Summary Liberty (according to merriam-webster dictionary) refers to: 1: the quality or state of being free: a: the power to do as one pleases b: freedom from physical restraint c: freedom from arbitrary or despotic (see DESPOT sense 1) control d: the positive enjoyment of various social, political, or economic rights and privileges e: the power of choice Isaiah Berlin's positive and negative liberty can be thought of as "freedom to" and "freedom from". Negative liberty Berlin initially defined as freedom from, that is, the absence of constraints on the agent imposed by other people. Positive liberty he defined both as freedom to, that is, the ability (not just the opportunity) to pursue and achieve willed goals; and also as autonomy or self-rule, as opposed to dependence on others. Positive liberty "is involved in the answer to the question 'What, or who, is the source of control or interference that can determine someone to do, or be, this rather than that?'" Positive liberty may be understood as self-mastery. Berlin granted that both concepts of liberty represent valid human ideals, and that