In his preface to a corrected version of Aurelius Augustinus's (Augustine of Hippo's) De arte praedicandi (Book IV of De doctrina christiana) printed in Strassburg by Johann Mentelin not after 1466, an anonymous scholar described the value and difficulty of preparing as accurate a manuscript text as possible for printing, probably for the first time in any printed book:
"Nevertheless I have thought it by all means worthwhile that I should first expend much labour over what would be to the common utility of the Church: that I may have this most useful little book- worthy of all esteem - correct, in order that, after correction this way, I would be able to communicate it more usefully to all those wishing to have it. Therefore, as God is my witness, I have taken great pains in the correction of it, in such a way that I have sought out diligently all the copies which I have been able to discover for this purpose in any of the libraries in the school of Heidelberg, in Speyer and in Worms, and finally also in Strassburg. And since in the course of this I have learned by experience that that particular book of Augustine is rare to come by even in the great and well stocked libraries, and even rarer can it be had for copying from any of those same libraries; and also, what is worse, that when it can be found in there it is more rarely corrected or emended; on that account I have been moved to work most carefully to this end; that, according to my exemplar- now corrected at least by as much care and labour as I am capable of- the said little book can be multipled in this state, and in such a way that it may become rapidly and easily known in a short time, for the use of many and to the common advantage of the Church. On account of which, since I judged that this could not be done more expeditiously by any other method or means, I have persuaded by every means that discreet gentleman Johann Mentelin, inhabitant of Strassburg, master of the art of typography, to the end that the might see fit to undertake the responsibily and toil of multiplying this little book by means of printing, having my copy before his eyes. . . ." (M.B. Parkes, Introduction to Peter Ganz (ed) The Role of the Book in Medieval Culture  15-16).