General: The German word Illusion originally meant criticism of art as a mental delusion (Plato); in the 17th and 18th centuries, it came to denote trompe l'oeil art. In English illusion in the sense of “deceptive appearance” came into use in the 14th century.
Criticism of Metaphysics: British empiricism (I) employed illusions pejoratively in the sense of “erroneous notions.” T. Hobbes blamed the devil for the illusory allegorical misinterpretation of Scripture. J. Locke attacked illusion in the sense of imagination and poetry, and D. Hume attacked “illusions of …