It is not altogether easy to adjust the respective claims of society at large and of the individual thinker in the constitution of moral theory, or, in other words, to determine the limits within which the speculative moralist may legitimately endeavour to reform the existing moral sentiment. It is plain that it must be open to the moralist, and, in fact, to every intelligent citizen, to criticize the current morality, or else moral progress, even if it took place at all, would, on many points of conduct, be exceedingly slow. But, on the other hand, it is equally plain that a constant discussion of the accepted rules of conduct would weaken the moral sentiment, lessen the sense of obligation, and suggest a general uncertainty as to the validity of the maxims which, in their relations to one another, men usually take for granted. Hence, though it would be almost fatal to moral progress to discourage speculation on moral topics, the moralist must always bear in mind that his task is one which is not lightly to be undertaken, and that, with an exception to be noticed presently, the presumption should always be in favour of existing rules of conduct. If for no other reason, this presumption ought to be made on the practical ground that a disturbance of the moral sentiment on one point is likely to weaken its force generally, and, before we expose men to this danger, we ought to have some adequate justification. But there is also the speculative ground that any given society, and indeed mankind generally, has been engaged for ages in feeling its way, instinctively or semi-consciously, towards a solution of the self-same problems which the philosopher is attempting to solve consciously and of set purpose. That, on the whole, a society has solved these problems in the manner best suited to its existing needs and circumstances may fairly be taken for granted, and, even where the ethical stand-point of the reformer is very superior to the stand-point of the society which he wishes to reform, he will be wise in endeavouring to introduce his reforms gradually, and, if possible, in connexion with principles already acknowledged, rather than in attempting to effect a moral revolution, the ultimate results of which it may be impossible to foresee. The work of the moralist is, therefore, best regarded as corrective of, and supplementary to, the work which mankind is constantly doing for itself, and not as antagonistic to it. The method is the same in both cases: only it is applied semi-consciously, and merely as occasions suggest it, in the one case; consciously and spontaneously in the other. In both cases alike the guiding principle, whether of action or of speculation upon action, is the adaptation of conduct to surrounding circumstances, physical and social, with a view to promote, to the utmost extent possible, the well-being of the individual and of the society of which he is a member.