The ultimate origin of moral rules, I conceive, so far at least as science can trace them, is to be found in the effort of men to adapt themselves to the circumstances, social and physical, in which they are placed.  At first, probably, this process of adaptation was almost automatic and unconscious, but, when men once began consciously to adapt means to ends, they would soon begin to reflect on their acts, and to ask themselves the reasons why they had selected this course of conduct rather than another.  The justifying reasons of their past acts, like the impelling motives of their future acts, could have reference to nothing but the convenience or gratification of themselves or those amongst whom they lived.  And the acts which they justified in themselves they would approve of in others.  Here, then, already we have a test consciously applied to the estimation of conduct.  Experience shews that this or that action promotes some object which is included in the narrow conception of well-being entertained by the primitive man.  He, therefore, continues to act in accordance with the rule which prescribes it, or the habit from which it proceeds.  And, in like manner, if he finds from experience that the action does not promote that object, and he is free to exercise his own choice, he desists from it and, perhaps, tries the experiment of substituting another.  Now, in these cases, it is plain that any judgment which the man exercises independently, and apart from the society of which he is a member, is guided solely by the consideration whether the course of conduct is efficacious in attaining its end, that end being part of his conception of the well-being of himself, his family, or his tribe.  If he thinks about the matter for himself at all, this is the only consideration of which he can take account.  There are three courses open to him.  He need not reflect on the action at all, but simply follow in the wake of his neighbours (and this, of course, is far the commonest case); or, if there is any divergence of opinion about it amongst his neighbours, he may deliberate as to whose opinion it is safest to follow; or, lastly, he may consider for himself, whether the action is really the best means of attaining the end aimed at, that is to say, he may test the means by its conduciveness to the end, which is always, in some shape, the welfare of himself or others.  If he follows the opinion of others, it is plain that their opinion, so far as it has been formed independently, has been formed in the manner above described.  The only alternative, therefore, is between the acceptance of existing opinions, without any consideration or examination, and their reference to the conception of well-being, or however else the idea may be expressed, as a measure of their appropriateness and sufficiency.  The idea of well-being itself may be inadequate, and even in parts incorrect, and, as society advances, it is undoubtedly undergoing a constant process of expansion and rectification;