In the account referred to Professor Sidgwick says:--
“My first adhesion to a definite Ethical system was to the Utilitarianism of Mill: I found in this relief from the apparently external and arbitrary pressure of moral rules which I had been educated to obey, and which presented themselves to me as to some extent doubtful and confused; and sometimes, even when clear, as merely dogmatic, unreasoned, incoherent. My antagonism to this was intensified by the study of Whewell’s _Elements of Morality_ which was prescribed for the study of undergraduates in Trinity. It was from that book that I derived the impression--which long remained uneffaced--that Intuitional moralists were hopelessly loose (as compared to mathematicians) in their definitions and axioms.
The two elements of Mill’s view which I am accustomed to distinguish as Psychological Hedonism [that each man does seek his own Happiness] and Ethical Hedonism [that each man ought to seek the general Happiness] both attracted me, and I did not at first perceive their incoherence.
Psychological Hedonism--the law of universal pleasure-seeking--attracted me by its frank naturalness. Ethical Hedonism, as expounded by Mill, was morally inspiring by its dictate of readiness for absolute self-sacrifice. They appealed to different elements of my nature, but they brought these into apparent harmony: they both used the same words “pleasure,” “happiness,” and the persuasiveness of Mill’s exposition veiled for a time the profound discrepancy between the natural end of action--private happiness, and the end of duty--general happiness. Or if a doubt assailed me as to the coincidence of private and general happiness, I was inclined to hold that it ought to be cast to the winds by a generous resolution.
But a sense grew upon me that this method of dealing with the conflict between Interest and Duty, though perhaps proper for practice could not be final for philosophy. For practical men who do not philosophise, the maxim of subordinating self-interest, as commonly conceived, to “altruistic” impulses and sentiments which they feel to be higher and nobler is, I doubt not, a commendable maxim; but it is surely the business of Ethical Philosophy to find and make explicit the rational ground of such action.