No doubt physiology, especially the disturbances of memory through lesions in the brain, affords grounds for this hypothesis; nevertheless it does remain a hypothesis, the validity of which will be discussed at the end of this lecture.
If, then, there is to be some standing difference between the person who can remember a certain fact and the person who cannot, that standing difference must be, not in anything mental, but in the brain. It is quite probable that there is such a difference in the brain, but its nature is unknown and it remains hypothetical.
If there are to be purely psychological causal laws, taking no account of the brain and the rest of the body, they will have to be of the form, not "X now causes Y now," but--
They are explained without it by Semon's "engram," or by any theory which regards the results of experience as embodied in modifications of the brain and nerves.
What we know is that memory, and mnemic phenomena generally, can be disturbed or destroyed by changes in the brain. This certainly proves that the brain plays an essential part in the causation of memory, but does not prove that a certain state of the brain is, by itself, a sufficient condition for the existence of memory.
In order to prove conclusively that mnemic phenomena arise whenever certain physiological conditions are fulfilled, we ought to be able actually to see differences between the brain of a man who speaks English and that of a man who speaks French, between the brain of a man who has seen New York and can recall it, and that of a man who has never seen that city.
Brain managed to secure his assembly of all the distracted company before the arrival of the police.
"We don't want to jump to any conclusions about anybody," Brain was saying in his staccato style.
He approached the group slowly, but with composure; but he was decidedly pale, and the eyes of Brain and Fisher had already taken in one detail of the green-clad figure more clearly than all the rest.
Rather to the surprise of the company, Brain did not follow up the question thus suggested; but, while retaining an air of leading the inquiry, had also an appearance of changing the subject.
Neither Brain nor Fisher exhibited any surprise, but the former added, quietly: