But, say you, surely there is nothing easier than for me to imagine trees, for instance, in a park [. . .] and nobody by to perceive them. [...] The objects of sense exist only when they are perceived; the trees therefore are in the garden [. . .] no longer than while there is somebody by to perceive them.
George BerkeleyThe question between the materialists and me is not, whether things have a real existence out of the mind of this or that person, but whether they have an absolute existence, distinct from being perceived by God, and exterior to all minds.
George Berkeley