In investigating the development of Christianity up till about the year 270 the following facts must be specially kept in mind: In the regions subject to Rome, apart from the Judaeo-Christian districts and passing disturbances, Christianity had yet an undivided history in vital questions;[300] the independence of individual congregations and of the provincial groups of Churches was very great; and every advance in the development of the communities at the same time denoted a forward step in their adaptation to the existing conditions of the Empire. The first two facts we have mentioned have their limitations. The further apart the different Churches lay, the more various were the conditions under which they arose and flourished; the looser the relations between the towns in which they had their home the looser also was the connection between them. Still, it is evident that towards the end of the third century the development in the Church had well-nigh attained the same point everywhere--except in outlying communities. Catholicism, essentially as we conceive it now, was what most of the Churches had arrived at. Now it is an _a priori_ probability that this transformation of Christianity, which was simply the adaptation of the Gospel to the then existing Empire, came about under the guidance of the metropolitan Church,[301] the Church of Rome; and that "Roman" and "Catholic" had therefore a special relation from the beginning. It might _a limine_ be objected to this proposition that there is no direct testimony in support of it, and that, apart from this consideration, it is also improbable, in so far as, in view of the then existing condition of society, Catholicism appears as the _natural and only possible_ form in which Christianity could be adapted to the world. But this is not the case; for in the first place very strong proofs can be adduced, and besides, as is shown by the development in the second century, very different kinds of secularisation were possible. In fact, if all appearances are not deceptive, the Alexandrian Church, for example, was up to the time of Septimius Severus pursuing a path of development which, left to itself, would _not_ have led to Catholicism, but, in the most favourable circumstances, to a parallel form.[302]