THERE are two points of view in which every system may be regarded—its external action, and its internal principle. We may examine either the great effects of its machinery, its plans, its purposes, its advances, and its perils; or we may trace its inner principle, and endeavour to detect the secret spring by which the whole is set in motion. It must at once be obvious that this latter inquiry is by far the more difficult; for our attention is directed rather to the philosophy than the action of the system; and we are called to examine the subtle tendencies of the human heart, which, of course, are more difficult both of detection and exhibition than the great, broad, startling facts which lie on the surface of the world’s history. This difficulty I have seriously felt in the preparation of the present lecture, the subject of which, is, “Popery the accommodation of Christianity to the natural heart.” The subject plainly requires that we should study the secret working of the natural heart, and should also examine into the corresponding principles of Popery, in order to discover their mutual accommodation, and to show how the whole system of the one is dexterously fitted to allay the fears and supply the cravings of the other. Throughout, therefore, we have to deal more with principles than with facts. I must ask your forbearance, therefore, if the lecture assumes a somewhat abstract form, and contains but few of those startling statements which abound in the history of Popery, and which are of the utmost importance in arousing the dormant Protestantism of the land. But yet, as facts are but the development of principles, I must ask the attention of thinking minds, and earnestly beg the candid consideration of all those Christian friends, whose desire it is to be established in the truth.