Object-oriented ontology (OOO) or object-oriented philosophy, developed by the philosopher Graham Harman in the past two decades, is one of the most exciting new theories in and beyond philosophy. Harman refers to an object as a unified reality (physical or otherwise) that cannot fully be reduced either downwards to its pieces or upwards to its effects. An object may be human, non-human, natural, cultural, real or fictional. It is either real or sensual kind. A real object exists regardless whether it affects anything else, while a sensual object exists only in relation to a real object. The properties of an object also come in two kinds: real and sensual. An object is not identical with its properties. Neither can humans directly encounter with a real object, nor they can completely understand the real qualities of an object. To gain access to a real object and real qualities, humans cannot just rely on the various models of knowledge; instead, they also need to find an aesthetic path of wisdom. This lecture first discusses the intellectual genealogy of object-oriented ontology and then clarifies its differences from such concepts as “posthumanism” and “the Anthropocene,” and such theories as “new materialism” and “new realism.” The lecture aims at exploring ways in which art is both a technology of engagement and an aesthetic path of encountering real objects and real qualities.