INCOMPREHENSIBLES — CORNER 245 



fore sensitive, tissues and their coordination by equally complex and 

 unstable tissues such as nerves and blood vessels. At the level of the 

 mind, the structure in which thinking is done is no less complicated. 

 Dr. Karl Lashley, in a pioneering essay "In Search of the Engram," 

 on the physiological basis of learning, closely estimated the number 

 of nerve cells in the visual apparatus of the white rat from retina to 

 brain cortex, and got a total of thirteen millions. With these neurones 

 the rat is able to retain (says Lashley) scores, perhaps hundreds of 

 visual habits involving discrimination of complex figures. The rhesus 

 monkey has about a hundred times as many visual neurones ; man, we 

 may conjecture, a thousand times thirteen millions. A student read- 

 ing his textbooks instantly distinguishes any one of ten thousand pat- 

 terns presented by the printed words before him. 



This enormous, overwhelming, almost inconceivable complexity of 

 the human structure and mental function forces us, if we are to be 

 materialists, into materialism of a new sort. "Wlien La Mettrie said 

 that man is a machine, a machine to him meant something like a clock 

 or the primitive Newcomen steam engine. He must have realized that 

 the human machine is more complicated than that, but still it was to 

 him, figuratively, a thing of cogs and levers. If, however, I say that 

 man is a machine, I have to think of an apparatus much more com- 

 plicated than the biggest electronic computing machine, and also much 

 less stable, much more sensitive than any piece of man-made automatic 

 hardware. The difference between old and new concepts of the living 

 machine is so great, so fundamental, that twentieth-century scientific 

 materialism is bound to be very different from that of the past. My 

 variety of it, you may say when I fijiish, is not materialism at all. 



Mention of electronic calculating machines brings us to the most 

 recent aspect of mechanistic thought, the kind of analysis called cyber- 

 netics. This stems from the observation of certain similarities between 

 electronic circuits and the structure and functioning of the nervous 

 system. Not only is the transmission of the nerve impulse analogous 

 to the electric current; not only are the synapses or nerve junctions 

 analogous to electrical connections, and the primary reflex arc merely 

 a doorbell circuit ; more than that, something much like feedback wir- 

 ing and regenerative circuits can be seen in the brain, suggesting the 

 existence of stages of amplification like those of a radio set. On the 

 contrary, some of the mental activities of men and animals can be 

 imitated by machines built on these principles : for example, simple 

 remembering, simple discriminations, even choice between alternatives 

 simply presented. Some of these operations are fairly impressive. 

 Everyone has heard what the great computing machines can do, for 

 example, in solving complicated differential equations in a fraction of 

 d second. Wlien a wartime committee under my direction was study- 

 ing devices for the blind, the engineer Zworykin of the Radio Corpora- 



