are clearly physical states and processes--not merely neural--in the organism of the sentient individual: and this is also true of a more indefinite kind of pleasure, which is an important element of ordinary human happiness,--the “well-feeling” that accompanies and is a sign of physical well-being. On the other hand, when we investigate the causes of the pleasures and pains that belong to intellectual exercises or the play of personal affections,--or of the pleasures (and to some extent pains) that belong to the contemplation of beauty (or its opposite) in art or nature,--no physiological theory can carry us far, owing to our ignorance of the neural processes that accompany or antecede these feelings. This is my general conclusion: the grounds for which I propose to illustrate and explain further in the present chapter. It would, however, seem to be quite beyond my limits to attempt anything like an exhaustive discussion of either psychological or physiological theories of the causes of pleasure and pain. I shall confine myself to certain leading generalisations, which seem to have a special interest for students of ethics; either because ethical motives have had a share in causing their acceptance; or because--though inadequately grounded as general theories--they appear to have a partial and limited value for practical guidance. § 2. Let us begin by considering a theory, primarily psychological, which has at least the merit of antiquity--as it is admittedly derived from Aristotle,[133]--and is, in some form or other, still current.[134] It is that expressed by Sir W. Hamilton[135] in the following propositions: “Pleasure is the reflex of the spontaneous and unimpeded exertion of a power of whose energy we are conscious: pain, a reflex of the overstrained or repressed exertion of such a power.” The phrases suggest _active_ as ordinarily distinguished from _passive_ states; but Hamilton explains that “energy” and similar terms “are to be understood to denote indifferently all the processes of our higher and lower life of which we are conscious,”--on the ground that consciousness itself implies more than a mere passivity of the subject. I think, however, that the theory is evidently framed primarily to suit the pleasures and pains that belong to the intellectual life as such, and is only applied by a somewhat violent straining to an important class among the pleasures and pains that belong to man’s animal life. For Hamilton explains his terms (_a_) “spontaneous” and (_b_) “unimpeded” to imply respectively (_a_) absence of “forcible repression” or “forcible stimulation” of the power exercised, and (_b_) absence of checks or hindrances on the part of the object about which it is conversant. But these terms seem to have no clear psychical import in application to organic sensations of the kind ordinarily called passive. _E.g._ the feelings and vague representations of bodily processes which constitute the consciousness of a toothache are as free