George Berkeley

Berkeley pushed empiricism to its startling edge. If all we ever know are our perceptions, he reasoned, then there is no warrant for a dead material substance lurking behind them; to exist is to be perceived. The world is real but mental, a steady stream of ideas held in being by the perceiving of God. Critics thought it absurd and could not say where the argument went wrong, which is its own kind of victory. An Irish bishop who later schemed to found a college in Bermuda, he wrote with a clarity that makes the strangeness of his conclusion all the sharper.