What is the human mind? In view of the variety of answers given in the history of philosophy, no definite answer appears to be possible. This is however in itself a significant answer to the question. If it is true ontological statements about the mind are always provisional or at most valid only for a certain period of time. Or, in view of the revival now and then of historical theories of the mind, it is even conceivable that such theories, after having been false for alonger or shorter period of time, may become true again.