Things perceived by the senses are immediately perceived by the senses; and things immediately perceived by the senses are ideas; and ideas cannot exist without the mind, their existence therefore consists in being perceived; when therefore they are actually perceived, there can be no doubt of their existence.
ATTRIBUTION:
George Berkeley (1685–1753), Irish divine, philosopher. Three Dialogues Between Hylas and Philonous, “Third Dialogue,” p. 220, Philosophical Works, ed. Michael R. Ayers, Everyman, J.M. Dent, London (1993).
