Can we now say anything definite about _the nervous correlate of the simple feelings_? Can we say what is going on in the nervous system when we feel pleasantly or unpleasantly? Unfortunately no: _we have many theories, but no positive knowledge_. There is, however, one view of feeling which has persisted from Aristotle to the present day; and we must say a word about it, if only because you cannot read far in psychology without running against some form of it, and you should not blindly accept it. We may call it the =biological theory= of feeling. Aristotle said that pleasure (we must now use the old-fashioned terms) accompanies the unimpeded exercise of any faculty, that is, the healthy exercise of any mental faculty upon its appropriate object; and that pain accompanies impeded activity. In more modern language, pleasure is for Aristotle a matter of efficiency. Herbert Spencer puts the same idea into evolutionary language; “pains are the correlatives of actions injurious to the organism, while pleasures are the correlatives of actions conducive to its welfare.” Does this statement really mean, though, that a man’s personal pleasures are always good for him and his personal pains bad for him?—because, if that is meant, it is not difficult to think of any number of cases to the contrary. No, not quite that; Spencer would qualify by saying that nature can only strike an average for the species; she cannot attend in detail to the individual; the sentence means that on the whole, in the long run, pleasures are good and pains are bad for us. We might reply that it is rather a poor average that makes the tearing off of a finger nail so exquisitely painful, though the loss hardly matters, and that allows the ravages of pulmonary tuberculosis to run so long a course before warning is given to the suffering organism. But let us offer a definite objection: a surgical operation is not pleasant; yet it may be the one thing necessary to save life. Spencer has his answer: “special and proximate pleasures and pains must be disregarded out of consideration for remote and diffused pleasures and pains.” In that case, however,—if the feelings are merely witnesses to the state of affairs at the moment, and not prophets of the future,—the correlation does not help us very much; nature’s achievement is less important, even for the species, than it seemed at first. Or take another objection: I am overheated, and I sit in a cooling draught; the result is catarrh or pneumonia; yet the coolness was pleasant. To be sure, says the biologist; and the local effect was good for you; the testimony of the feelings is limited in space as I have just acknowledged it to be limited in time. Again, however, we must rejoin that, in that event, the correlation is of less importance to the race than it was asserted to be; if things that are ‘sweet in the mouth’ are going to be ‘bitter in the belly’ we want to know it; it is small comfort to be told that