By the help of the preceding operations the documents, all the documents, let us suppose, of a given class, or relating to a given subject, have been found. We know where they are; the text of each has been restored, if necessary, and each has been critically examined in respect of authorship. We know where they have come from. It remains to combine and classify the materials thus verified. This is the last of the operations which may be called preparatory to the work of higher (or internal) criticism and construction. Whoever studies a point of history is obliged, first of all, to classify his sources. To arrange, in a rational and convenient manner, the verified materials before making use of them, is an apparently humble, but really very important, part of the historian's profession. Those who have learnt how to do it possess, on that account alone, a marked advantage: they give themselves less trouble, and they obtain better results; the others waste their time and labour; they are smothered sometimes under the disorderly mass of notes, extracts, copies, scraps, which they themselves have accumulated. Who was it spoke of those busy people who spend their lives lifting building-stones without knowing where to place them, raising as they do so clouds of blinding dust? I. Here, again, we have to confess that the first, the natural impulse, is not the right one. The first impulse of most men who have to utilise a number of texts is to make notes from them, one after another, in the order in which they study them. Many of the early scholars (whose papers we possess) worked on this system, and so do most beginners who are not warned beforehand; the latter keep, as the former kept, note-books, which they fill continuously and progressively with notes on the texts they are interested in. This method is utterly wrong. The materials collected must be classified sooner or later; otherwise it would be necessary, when occasion arose, to deal separately with the materials bearing on a given point, to read right through the whole series of note-books, and this laborious process would have to be repeated every time a new detail was wanted. If this method seems attractive at first, it is because it appears to save time. But this is false economy; the ultimate result is, an enormous addition to the labour of search, and great difficulty in combining the materials.