THE STREAM OF THOUGHT. 235 sounds alters our feeling of another ; so, in thought, we must admit that those portions of the brain that have just been maximally excited retain a kind of soreness which is a condition of our present consciousness, a codeterminant of how and what we now shall feel.* Ever some tracts are waning in tension, some waxing, whilst others actively discharge. The states of tension have as positive an influence as any in determining the total condition, and in deciding what the psychosis shall be. All we know of submaximal nerve-irritations, and of the summation of apparently ineffective stimuli, tends to show that no changes in the brain are physiologically ineffective, and that presumably none are bare of psychological result. But as the brain-tension shifts from one relative state of equilibrium to another, like the gyrations of a kaleido- scope, now rapid and now slow, is it likely that its faithful psychic concomitant is heavier-footed than itself, and that it cannot match each one of the organ's irradiations by a shifting inward iridescence of its own ? But if it can do this, its inward iridescences must be infinite, for the brain- redistributions are in infinite variety. If so coarse a thing as a telephone-plate can be made to thrill for years and never reduplicate its inward condition, how much more must this be the case with the infinitely delicate brain ? I am sure that this concrete and total manner of regard- ing the mind's changes is the only true manner, difficult as it may be to carry it out in detail. If anything seems ob- scure about it, it will grow clearer as we advance. Mean- while, if it be true, it is certainly also true that no two 'ideas' are ever exactly the same, which is the proposition we started to prove. The proposition is more important theoretically than it at first sight seems. For it makes it
- It need of course not follow, because a total brain-state does not re-
cur, that no point of the brain can ever be twice in the same condition. That would be as improbable a consequence as that in the sea a wave-crest should never come twice at the same point of space. What can hardly- come twice is an identical combination of wave-forms all with their crests and hollows reoccupyiug identical places. For such a total combina- tion as this is the analogue of the brain-state to which our actual conscious- ness at any moment is due.
