First of all, the so-called "auxiliary sciences" are not all of them _sciences_. Diplomatic, for example, and the History of Literature are only systematised accumulations of facts, acquired by criticism, which are of a nature to facilitate the application of critical methods to documents hitherto untouched. On the other hand, Philology is an organised science, and has its own laws. In the second place, among the branches of knowledge auxiliary--properly speaking, not to history, but to historical research--we must distinguish between those which every worker in the field ought to master, and those in respect of which he needs only to know where to look when he has occasion to make use of them; between knowledge which ought to become part of a man's self, and information which he may be content to possess only in potentiality. A mediævalist should _know_ how to read and understand mediæval texts; he would gain no advantage by accumulating in his memory the mass of particular facts pertaining to the History of Literature and Diplomatic which are to be found, in their proper place, in well-constructed works of reference. Lastly, there are no branches of knowledge which are auxiliary to History (or even historical research) in general--that is, which are useful to all students irrespectively of the particular part of history on which they are engaged.[48] It appears, then, that there is no general answer possible to the question raised at the beginning of this chapter: in what should the technical apprenticeship of the scholar or historian consist? In what does it consist? That depends. It depends on the part of history he proposes to study. A knowledge of palæography is quite useless for the purpose of investigating the history of the French Revolution, and a knowledge of Greek is equally useless for the treatment of a question in mediæval French history.[49] But we may go so far as to say that the preliminary outfit of every one who wishes to do original work in history should consist (in addition to the "common education," that is, general culture, of which Daunou writes) in the knowledge calculated to aid in the discovery, the understanding, and the criticism of documents. The exact nature of this knowledge varies from case to case according as the student specialises in one or another part of universal history. The technical apprenticeship is relatively short and easy for those who occupy themselves with modern or contemporary history, long and laborious for those who occupy themselves with ancient and mediæval history.