"If unity lies in the Apostolic succession, an act of schism is from the nature of the case impossible; for as no one can reverse his parentage, so no Church can undo the fact that its clergy have come by lineal descent from the Apostles. Either there is no such sin as schism, or unity does not lie in the episcopal ordination. And this is felt by the controversalists alluded to; who in consequence are obliged to invent a sin, and to consider, not division of church from church, but the interference of church with church to be the sin of schism, as if local dioceses and bishops with restraint were more than ecclesiastical arrangements, and by-laws of the Church, however sacred, while schism is a sin against her essense. Thus they strain out a gnat, and swallow a camel. Division is the schism, if schism there be, not interference. If interference is a sin, division which is the cause of it is a greater, but where division is a duty, there can be no sin in inteference."
John Henry Newman, An essay on the development of Christian doctrine: the edition of 1845, ed. J. M. Cameron (Harmondsworth, Middlesex, England: Penguin Books, 1974), 286 (IV.ii).