The colophon to a Strassburg edition of the sermons known by the title “Dormi secure” tells us that it was issued “secunda feria post Laetare” in the same year 1493. “Laetare” being the first word of the introit for the fourth Sunday in Lent, it thus appeared on Monday, March 18th, exactly a fortnight after the “Postilla” of Guillermus. So again we find Hans Schauer of Augsburg dating an edition of a “Beichtbuchlein,” or manual of confession, “am Samstag vor Invocavit in dem XCij. iar,”—on Saturday before Invocavit, 1492,—which gives the date (Invocavit marking the first Sunday in Lent and Easter in 1492 falling on April 22d), Saturday, March 10th. It is generally only the introits of the first four Sundays in Lent (Invocavit, Reminiscere, Oculi, and Laetare) and that of the first Sunday after Easter (Quasimodo) that are used in colophons in this way. We may bring this chapter to an end by noting one or two fruitful causes of error in dating books which arise from misunderstanding the reference or meaning of the dates in their colophons. In Chapter VI it has already been noted that where an author or editor has given the date on which he finished writing, such a date has often been confused with the date of imprint. More dangerous but much rarer than such a pitfall as this is the case of the reprinted colophon (see Chapter VII), which can be detected only by experts in typography. The majority of mistakes, however, arise from very simple misreadings. In many fifteenth-century fonts of type the symbols x and v are very imperfectly distinguished, so that the five has often been mistaken for a ten. Modern eyes, again, being used to the symbols iv, ix, xl, are very apt to read the fifteenth-century iiii as iii, the viiii as viii, and the xxxx as xxx. On the other hand, as they neared the end of the century the printers not only expressed ninety-nine by ic, but also used the forms vc, iiiic, iiic, iic, to express the years ’95 to ’98; and, as has been done here for the sake of brevity, occasionally omitted the precedent Mcccc., as in the “in dem XCij. iar” of the colophon of the “Beichtbuchlein,” quoted a page or two back. They also, it may be noted, frequently expressed eighty by the reasonable symbol for fourscore, or quatre vingt—namely, iiiixx. These latter methods of writing dates, however, though they may puzzle for a moment, can hardly mislead; but in the case of books issued in the years 1470, 1480, 1490, and 1500 (more especially the last) there is one error so easily made that it has left its mark on every old catalogue of incunabula. Thus when Hermann Lichtenstein dated an edition of the “Opuscula” of S. Thomas Aquinas “anno salutis M.cccc.xc. vii Idus septembris” he encouraged any ignorant or careless cataloguer to misread the date as 1497 on the “Ides of September,” instead of 1490 on the seventh day before the “Ides of September.” The mistake may be made just as easily when words are used instead of numerals, for “anno nostre