person; that though the characters of historian and scholar may be combined, there is nothing illegitimate in their separation; and that perhaps this separation is desirable in theory, as, in practice, it is often a necessity. In practice, what happens is as follows. Whatever part of history a man undertakes to study, there are only three possible cases. In the first the sources have already been emended and classified; in the second the preliminary work on the sources, which has been only partially done, or not at all, offers no great difficulty; in the third the sources are in a very bad state, and require a great deal of labour to fit them for use. We may observe, in passing, that there is naturally no proportion between the intrinsic importance of the subject and the amount of preliminary work which must be done before it can be treated: there are some subjects of the highest interest, for example the history of the origin and early development of Christianity, which could not be properly attacked till after the completion of investigations which occupied several generations of scholars; but the material criticism of the sources of the history of the French Revolution, another subject of the first rank, gave much less trouble; and there are comparatively unimportant problems in mediæval history which will not be solved till after an immense amount of external criticism shall have been performed. In the two first cases the expediency of a division of labour does not come in question. But take the third case. A man of ability discovers that the documents which are necessary for the treatment of a point of history are in a very bad condition; they are scattered, corrupt, and untrustworthy. He must take his choice; either he must abandon the subject, having no taste for the mechanical operations which he knows to be necessary, but which, as he foresees, would absorb the whole of his energy; or else he resolves to enter upon the preparatory critical work, without concealing from himself that in all probability he will never have time to utilise the materials he has verified, and that he will therefore be working for those who will come after him. If he adopts the second alternative he becomes a critical scholar by profession, as it were in spite of himself. _A priori_, it is true, there is nothing to prevent those who make great collections of texts and publish critical editions from using their own compilations and editions for the writing of history; and we see, as a matter of fact, that several men have divided themselves between the preparatory tasks of external criticism and the more exalted labours of historical construction: it is enough to mention the names of Waitz, Mommsen, and Hauréau. But this combination is very rare, for several reasons. The first is the shortness of life; there are catalogues, editions, _regesta_ on a great scale, the construction of which entails so much mechanical labour as to exhaust