Mathematical Treasures - The Art of Numbering (anonymous)
The author of Ars numerandi (The Art of Numbering), published in 1482, remains unknown; however, the text is usually associated with its printer/publisher Ulrich Zel (d. 1503), the first printer in Cologne. Here are the first two pages of this work:
The images above are provided courtesy of Columbia University Libraries, George Arthur Plimpton Collection.