And, in explaining why pleasure and pain cannot be regarded as "the sovereign masters" of ethic, we may add to the evidence for our conclusion. It appears that Bentham and his school do not observe the proprieties of language in identifying the moral good, the moral right, with pleasure. The ideas are really incommensurate, as is well pointed out in Schurman's monograph on the Kantian and the evolutionary ethics of Spencer. The ethical "ought," the word which gives the keynote to the whole science, does not and cannot mean what is "pleasurable," "serviceable," or "useful". The word essentially implies the "ideal," the conformity to a definite standard of right, the approximation towards a goal or standard of conduct implicitly recognised as absolute good. But the ideas of "pleasurable," "useful," and the like concern the moment only; they merely suggest that man should secure the advantage offered or avoid the pain which may befall him here and now, or some time subsequently to his contemplated action. Hence there is no obligatory force in this ethic. Prudential motives, suggestions of expediency, abundance of counsel, if you will; but we miss the note of authority, the commanding voice, the categorical imperative, the solemn injunction, "Thou canst, therefore thou must". Indeed, it seems difficult to see how one could convince a man on hedonistic or utilitarian grounds that a course of conduct on which he was bent, and to which he was allured by the overmastering impulse of a vehement nature, and which promised him sensible gratification, possibly even material advancement, was not legitimate. I do not press this, nor do I suggest that moral elevation of life is not discernible amongst professors of this interpretation of ethics equally with those who take an idealist view. All I say is, that the recognised terminology of the ethical life, the "ought," the "must," receive an ampler recognition, a fuller interpretation, in the rational schools than in those of Bentham and Spencer.