Idealism

Idealism is the philosophical theory which maintains that experience is ultimately based on mental activity. In the philosophy of perception, idealism is contrasted with realism, in which the external world is said to have an apparent absolute existence. Epistemological idealists (such as Kant) claim that the only things which can be directly known for certain are just ideas (abstraction). In literature, idealism refers to the thoughts or the ideas of the writer.
In the philosophy of mind, idealism is the opposite of materialism, in which the ultimate nature of reality is based on physical substances. Idealism and materialism are both theories of monism as opposed to dualism and pluralism. Idealism sometimes refers to a tradition in thought that represents things of a perfect form, as in the fields of ethics, morality, aesthetics, and value. In this way, it represents a human perfect being or circumstance.
Idealism is a philosophical movement in Western thought, and names a number of philosophical positions with sometimes quite different tendencies and implications in politics and ethics; for instance, at least in popular culture, philosophical idealism is associated with Plato and the school of platonism.