In order to draw legitimate inferences from a document to the fact of which it is the trace, numerous precautions are requisite which will be indicated in the sequel. But it is clear that, prior to any critical examination or interpretation of documents, the question presents itself whether there are any documents at all, how many there are, and where they are. If I undertake to deal with a point of history,[22] of whatever nature, my first step will be to ascertain the place or places where the documents necessary for its treatment, if any such exist, are to be found. The search for and the collection of documents is thus a part, logically the first and most important part, of the historian's craft. In Germany it has received the convenient, because short, name of _Heuristik_. Is there any need to prove the capital importance of Heuristic? Assuredly not. It is obvious that if it is neglected, if the student does not, before he sets to work on a point of history, place himself in a position to command all accessible sources of information, his risk (no small one at the best) of working upon insufficient data is quite unnecessarily increased: works of erudition or history constructed in accordance with the rules of the most exact method have been vitiated, or even rendered worthless, by the accidental circumstance that the author was unacquainted with the documents by which those which he had within reach, and with which he was content, might have been illustrated, supplemented, or discredited. The scholars and historians of to-day, standing, as they do, in other respects on an equality with their predecessors of the last few centuries, are only enabled to surpass them by their possession of more abundant means of information.[23] Heuristic is, in fact, easier to-day than it used to be, although the honest Wagner has still good grounds for saying: "Wie schwer sind nicht die Mittel zu erwerben, Durch die man zu den Quellen steigt!"[24] Let us endeavour to explain why the collection of documents, once so laborious, is still no easy matter, in spite of the progress made in the last century; and how this essential operation may, in the course of continued progress, be still further simplified.