be tolerated, even preferred by cultivated readers. They take away the taste for other books, as G. Paris very well says: "When one has feasted on these substantial pages, so full of facts, which, with all their appearance of impersonality, yet contain, and above all suggest, so many thoughts, it is difficult to read books, even books of distinction, in which the subject is cut up symmetrically to fit in with a preconceived system, is coloured by fancy, and is, so to speak, presented to us in disguise, books in which the author continually comes between us and the spectacle which he claims to make intelligible to us, but which he never allows us to see." The great historical "manuals," uniform with the treatises and manuals of the other sciences (with the added complication of authorities and proofs), ought to be, and are, continually improved, emended, corrected, brought up to date: they are, by definition, works of science and not of art.
The earliest repertories and the earliest scientific "manuals" were composed by isolated individuals. But it was soon recognised that a single man cannot correctly arrange, or have the proper mastery over a vast collection of facts. The task has been divided. Repertories are executed, in our days, by collaborators in association (who are sometimes of different nationalities and write in different languages). The great manuals (of I. von Müller, of G. Gröber, of H. Paul, and others) are collections of special treatises each written by a specialist. The principle of collaboration is excellent, but on condition (1) that the collective work is of a nature to be resolved into great independent, though co-ordinated, monographs; (2) that the section entrusted to each collaborator