part of our mental constitution, on which is founded our conviction of first truths, and that principle from which is derived our impression of moral truth:--For the former continues the same in every mind which is neither obscured by idiocy nor distorted by insanity; but the moral feelings become vitiated by a process of the mind itself, by which it has gradually gone astray from rectitude. Hence the difference we find in the decisions of different men, respecting moral truth, arising from peculiarities in their own mental condition;--and hence that remarkable obscuration of mind, at which some men at length arrive, by which the judgment is entirely perverted respecting the first great principles of moral purity. When, therefore, we appeal to certain principles in the mental constitution, as the source of our first impressions of moral truth, our appeal is made chiefly to a mind which is neither obscured by depravity, nor bewildered by the refinements of a false philosophy:--it is made to a mind in which conscience still holds some degree of its rightful authority, and in which there is a sincere and honest desire to discover the truth. These two elements of character must go together in every correct inquiry in moral science; and, to a man in an opposite condition, we should no more appeal, in regard to the principles of moral truth, than we should take from the fatuous person or the maniac our test of those first principles of intellectual truth, which are allowed to be original elements of belief in every sound mind. To remedy the evils arising from this diversity and distortion of moral perception, is one of the objects of divine revelation. By means of it there is introduced a fixed and uniform standard of moral truth; but, it is of importance to remark, that, for the authority of this, an appeal is made to principles in the mind itself, and that every part of it challenges the assent of the man in whom conscience has not lost its power in the mental economy. * * * * * Keeping in view the distinction which has now been referred to, it would appear, that there are certain first principles of moral truth, which arise in the mind by the most simple process of reflection,--either as constituting its own primary moral convictions, or as following from its consciousness of these convictions by a plain and obvious chain of relations. These are chiefly the following. I. A perception of the nature and quality of actions, as just or unjust,--right or wrong;--and a conviction of certain duties, as of justice, veracity, and benevolence, which every man owes to his fellow-men. Every man, in his own case, again, expects the same offices from others; and, on this reciprocity of feeling, is founded the precept, which is felt to be one of universal obligation, to do to others as we would that they should do to us.