work, and the scholar who
compiles "_Regesta_." By the words "_Regesta_" and "_Corpus_" we
understand methodically classified collections of historical documents.
In a "_Corpus_" documents are reproduced _in extenso_; in "_Regesta_"
they are analysed and described.

The use of these compilations is to assist researchers in collecting
documents. Scholars set themselves to perform, once for all, tasks of
search and classification from which, thanks to them, the public will
henceforth be free.

Documents may be grouped according to their date, according to their
place of origin, according to their contents, according to their
form.[97] Here we have the four categories of time, place, species, and
form; by superposing, then, we obtain divisions of smaller extent. We
may undertake, for example, to make a group of all the documents having
a given form, of a given country, and lying between two given dates
(French royal charters of the reign of Philip Augustus); or of all the
documents of a given form (Latin inscriptions); or of a given species
(Latin hymns); of a given epoch (antiquity, the middle ages). We may
recall, by way of illustration, the existence of a _Corpus Inscriptionum
Graecarum_, of a _Corpus Inscriptionum Latinarum_, of a _Corpus
Scriptorum Ecclesiasticorum Latinorum_, the _Regesta Imperii_ of J. F.
Boehmer and his continuators, the _Regesta Pontificum Romanorum_ of P.
Jaffe and A. Potthast.

Whatever the division chosen, there are two alternatives: either the
documents to be placed in this division are dated or they are not.

If they are dated, as is the case, for example, with the charters issued
from the chancery of a prince, care will have been taken to place at the
head of each slip the date (expressed in modern reckoning) of the
document entered upon it. Nothing is then easier than to group in
chronological order all the slips, that is, all the documents, which
have been collected. The rule is to use chronological classification
whenever possible. There is only one difficulty, and that is of a
practical order. Even in the most favourable circumstances some of the
documents will have accidentally lost their dates; these dates the
compiler is bound to restore, or at least to attempt to restore; long
and patient research is necessary for the purpose.

If the documents are not dated, a choice must be made between the
alphabetical, the geographical, and the systematic order. The history of
the _Corpus_