From the 1985 lecture programme:
The body consists of many different organs each composed of enormous numbers of living cells. Yet the whole is far more than a mere colony, for all its activities are tightly coordinated to act as an individual animal or person. This is only possible because of an elaborate communication system of nerves that transmit messages between all parts of the body and the brain.
We will examine how nerve cells conduct such messages at up to one third the speed of sound. Modern electronic methods and clinical computers allow us to observe nerve signals and to measure their effects entirely from outside the body surface, without any pain or surgery. We can even follow reflexes that act via the spinal cord to save time and only inform the brain later. For purposes where speed is less important, the brain also controls a system of chemical messengers or hormones that are carried around the body in the blood stream.
The brain itself is made of nerve cells and its operation depends upon the continuous processing of information, for decision making and control processes involve two way communication. As the ultimate controller of the body, the brain is responsible for maintaining all internal activities as well as reacting appropriately to what is happening in the environment. Each of us possesses the most advanced communication system ever known, perhaps the best we can even envisage.