incorrectly, and it was not always the fashion, as it was in the time of the Carlovingian Renaissance, to compare the copies with the originals.
If our printed books, after the successive revisions of author and printer's reader, are still but imperfect reproductions, it is only to be expected that ancient documents, copied and recopied as they have been for centuries with very little care, and exposed at every fresh transcription to new risk of alteration, should have reached us full of inaccuracies.
There is thus an obvious precaution to be taken. Before using a document we must find out whether its text is "sound"—that is, in as close agreement as possible with the original manuscript of the author; and when the text is "corrupt" we must emend it. In using a text which has been corrupted in transmission, we run the risk of attributing to the author what really comes from the copyists. There are actual cases of theories which were based on passages falsified in transmission, and which collapsed as soon as the true readings were discovered or restored. Printers' errors and mistakes in copying are not always innocuous or merely diverting; they are sometimes insidious and capable of misleading the reader.
One would naturally suppose that historians of repute would always make it a rule to procure "sound" texts, properly emended and restored, of the texts they have to consult. That is a mistake. For a long time historians simply used the texts which they had within easy reach, without verifying their accuracy. And, what is more, the very scholars whose business it is to edit texts did not discover the art of restoring them all at once; not so very long ago,