Main (Thompson) Library location: North wing -- First window. The earliest records concerning Arnold Therhoernen (c. 14-- – c. 1484) document him as a cleric of the Diocese of Utrecht who matriculated at the University of Cologne in 1468. He began to work at the press of Ulrich Zell, and the first known publication containing his name, Sermo de praesentatione beatae Mariae virginis, is dated to 1470. Cologne city records attribute over thirty titles to Therhoernen as an independent printer. In 1471, he printed his first independent book, Thomae de Aquino questiones de quodlibet. Three years later, Therhoernen published Fasciculus temporum by the Carthusian monk Werne Rolewinck. This popular book contained a meticulous Gothic typeface and also included the use of Arabic page numbers; it is unclear whether Zell or Therhoernen was the first to number the pages of text. Therhoernen continued to print until his death in 1484, issuing both philosophical and theological titles, including Soliloquia, Modus confitendi, and De vita et moribus philosophorum. For this unique mark, Therhoernen created a triangle in which two of the sides extend beyond their point of intersection to form tiny crosslets. Within the triangle is a star, and the initials A.H. appear on either side. A curved line on the right side suggests the outline of a heraldic crest. Therhoernen was one of the first Cologne printers to use a printer's mark in his colophon, and he often printed it in red.