The idea never was that throve and lasted, yet, like mathematical truth, incorporated nothing from external sources. So far from the fact of such incorporation implying corruption, as is sometimes supposed, development is a process of incorporation. Mahometanism may be in external developments scarcely more than a compound of other theologies, yet no one would deny that there has been a living idea somewhere in a religion, which has been so strong, so wide, so lasting a bond of union in the history of the world. Why it has not continued to develope after its first preaching, if this be the case, as it seems to be, cannot be determined without a greater knowledge of that religion, and how far it is merely political, how far theological, than we commonly possess. 3. In Christianity, opinion, while a raw material, is called philosophy or scholasticism; when a rejected refuse, it is called heresy. Ideas are more open to an external bias in their commencement than afterwards; hence the great majority of writers who consider the Medieval Church corrupt, trace its corruption to the first four centuries, not to what are called the dark ages. That an idea more readily coalesces with these ideas than with those does not show that it has been unduly influenced, that is, corrupted by them, but that it has an antecedent affinity to them. At least it shall be assumed here that, when the Gospels speak of virtue going out of our Lord, and of His healing with the clay which His lips had moistened, they afford instances, not of a perversion of Christianity, but of affinity to notions which were external to it; and that St. Paul was not biassed by Orientalism, though he said, after the manner of some Eastern sects, that it was "excellent not to touch a woman." 4.