Whenever I attempt to frame a simple idea of time, abstracted from the succession of ideas in my mind, which flows uniformly, and is participated by all beings, I am lost and embrangled in inextricable difficulties.
George BerkeleyBut, 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 Berkeley