Introduction : some perplexing discoveries -- Philosophical pictures : the birth of "the mind" -- Through pictures to problems : minds and bodies -- Pictures' effects : from "secondary qualities" to "perceptions" -- The power of pictures : Berkeley's approach -- Self-perpetuating absurdity : Berkeley defends "perceptions" -- Philosophical delusions : Ayer reinvents "perceptions" -- Two turns : a new vision of philosophy -- Linguistic analysis as therapy : Austin on "perceptions" -- Self-reflection as therapy : Wittgenstein on understanding.