With the previous chapter we came to the end of our study of how the organism changes from the unadapted to the adapted condition. But this simple problem and solution is only a first step towards our understanding of the living, and especially of the human, brain. To the simple ultrastable system we must obviously add further complications. Thus the living organism not only becomes adapted, but it does so by a process that shows some evidence of efficiency, in the sense that the adaptation is reached by a path that is not grossly far from the path that would involve the least time, and energy, and risk. Though ‘efficiency’ is not yet accurately defined in this context, few would deny that the Homeostat’s performance suggests something of inefficiency. But before we rush in to make ‘improvements’ we must be clear about what we are assuming.