The physiologists who, during the past few years, have been so industriously exploring the functions of the brain, have limited their attempts at explanation to its cognitive and volitional performances. Dividing the brain into sensorial and motor centres, they have found their division to be exactly paralleled by the analysis made by empirical psychology, of the perceptive and volitional parts of the mind into their simplest elements. But the aesthetic sphere of the mind, its longings, its pleasures and pains, and its emotions, have been so ignored in all these researches that one is tempted to suppose that if (physiological psychologists) were asked for a theory in brain-terms of the latter mental facts they might … reply either that they had as yet bestowed no thought upon the subject, or that they had found it so difficult to make distinct hypotheses that the matter lay for them among the problems of the future, only to be taken up after the simpler ones of the present should have been definitely resolved.

And yet it is even now certain that of two things concerning the emotions one must be true. Either separate and special centres affected to them alone are their brain-seat, or else they correspond to processes occurring in the motor and sensory centres, already assigned, or in others like them, not yet mapped out.