But it is our object to make this comparison and parallel between faith and infidelity, in the full practical meaning of the words, useful and historically applicable to life. For this purpose we must not regard infidelity as founded exclusively on caprice, aversion, or obstinacy--consequently on ignorance--but consider it rather as enjoying every intellectual advantage, and commanding all the resources of learning and science. For a purely personal, and merely negative unbelief, without any deep foundation, and without even an apparently scientific confirmation, is neither very dangerous to the community, and, above all, presents little if any interest to philosophy. But, on the other hand, if faith is successfully to cope with such an adversary, furnished with all the armor and expedients of science, it must be able to stand the comparison with it in this respect. It must, in short, be conceived and set forth in its natural relation to true science, and, taking its proper place and position, must act in union and co-operation with it. I must here, however, premise a second preliminary remark. I can not bring myself to follow a very general opinion, and look upon faith as a true and duly moderated medium between superstition and infidelity. On the contrary, I join superstition with infidelity, and can not but class them together. If by this term of superstition nothing is meant but some exaggeration or other, some over-excitement of the moral and religious feelings in individuals, then such a purely-personal case admits not of being raised to a general rule, nor elevated into a universal principle. And in any case it does not fall within the range of philosophical speculation. For the care of the spiritual health and healthy diet of the believing soul, which draws both life and love from the deep sources of faith, belongs to a wholly different province from that of philosophy. But by this word and notion of superstition there is often understood a very childish error, which does not duly separate and distinguish the figurative language and figurative forms of fancy from the substance of the true intrinsic meaning. This error, which thus confounds the figurative expression with reality, and takes it to be something real, may justly be called childish, inasmuch as it is universally peculiar, almost natural, to the intellect of children. Now, in and by itself, and simply understood, such an internal _optical delusion_ results from nothing but a psychological imperfection, or a mere semblance of intellectual nature. But when this error is carried out into a system, and applied, on a large scale, to the sum and essence of faith, then, undoubtedly, it possesses a profounder origin and significance. This species of superstition belongs to one of those classes of error which I am about to describe. When, for instance, an actual positive error is comprised in and understood by this name, then