George Berkeley

George Berkeley was an Irish philosopher and Anglican bishop who argued for a radical form of idealism: that material objects do not exist independently of minds perceiving them. His famous esse est percipi — "to be is to be perceived" — expressed his central claim that the apparent solidity of the physical world is entirely constituted by perception, sustained in its continuity by the mind of God. This seemingly paradoxical position was developed with considerable rigour in his Principles of Human Knowledge and Three Dialogues.