The importance of the comparative method in the process of sifting, classifying, and ordering the elements of these respective spheres will now be apparent. For it is only by a comparison of the varieties of Belief that we can hope to arrive at an acquaintance with Faith. Setting one system beside another, carefully observing wherein they differ and wherein they agree, we may at length hope to discover what elements, if any, are to be set down to the account of Faith, and what other elements to that of Belief. Even after a full comparison there will still be considerable danger that we may mistake tenets which are widely held, but not universal, for primordial conceptions of the human mind. Without such a comparison, we should most undoubtedly do so, for we are ever unwilling to recognize how wide are the limits of variation of which the opinions and sentiments of men are capable. Should we, however, succeed in eliminating by our analysis all that is local, and all that is temporary, we shall possess, in what remains to us after this process, a universal truth of human nature. Observe that I speak here of a truth of human nature as distinguished from a truth of external nature. The one does not of necessity imply the other, for it is conceivable that men might universally entertain certain hopes, fears, aspirations, or convictions which were wholly groundless; the supposed objects of which had no existence whatever beyond the mind that entertained them. In the present case, then, all that the most exhaustive comparison could do would be to lead us up to the scientific fact, that there is in human beings an irresistible tendency towards certain sentiments of a spiritual kind. Whether those sentiments can be the foundation of any rational conviction it is unable to tell us. This question, however, is fully as important as the other, and I do not propose to pass it over in silence. It will be one object of our investigation to discover how far we are entitled to treat truths of human nature as identical with objective truths. If we are obliged to confess that no inference can be drawn from the one to the other, then it will be plain that Faith, however profoundly implanted in our hearts, does not convey to us any assurance of a single religious truth; for the impressions which we call our Faith may be as purely illusory as the fancies of delirium, or the images of our dreams. If, on the other hand, an internal sentiment may be accepted, not so much as a basis for truth, but as itself true; as leading, and not misleading us; then we must further examine what are the truths which are in a manner contained in Faith, and of which Faith is the warrant.