Historically, the most complex piece of machinery of an epoch serves as a metaphor for the brain. The metaphor seems to take on a life of its own and becomes a neurophysiological model. In the eighteenth and nineteenth centuries the brain was often compared to a clock or chronometer. During the first part of the twentieth century the model usually was a telephone exchange, and since the 1950s a digital computer. Mechanical-biological analogies, of course, are not limited to neurophsyciology. Physicians bled feverish patients in the early nineteenth century because of a false analogy between blood temperature and steam engines. Early steem engines frequently exploded as pressure increased at high operating temperatures. Safety valves then were invented that released superheated pressure. Hence it followed that bleeding would reduce temperature. As a result of this false analogy, the chances of survival for soldiers wounded at Waterloo were greater if they had not been treated by surgeons immediately after battle. In its own way, the analogy between biological brains and digital comptuers is as fatal for understanding the neural bases of human language." (pp.23-24)