‘Calendarium’ is a work on astronomy by Johannes Regiomontanus (Johannes Müller) — an outstanding German mathematician and astronomer of the 15th century. ‘Regiomontanus’ is a Latinized form of the word ‘Königsberg’ — the name of the mathematician’s hometown.

Regiomontanus is known for his works on trigonometry, astronomy, and for his participation in the calendar reform development. The calendar, published in Latin, includes charts with images of lunar and solar eclipses, as well as movable astronomical tables and diagrams that specify the motion of celestial bodies. 

Regiomontanus’s Calendarium was published in 1476 by the famous Augsburg publisher Erhard Ratdolt, working in Venice at that period, and was the first printed publication with a title page.

Manuscript books had not known a title page, so familiar to us today. Usually, a manuscript would have started with the words: “Here begins…”. First printed books had followed this rule. The book’s title and the author’s name had been printed on the first page without any separation from the main text. The printer, time and place of publication might have been mentioned at the end, in the colophon.

Multiplication of publications changed the scenario. A popular and profitable book could be reprinted by different publishers, not always by conscientious ones. The buyer of the book was faced with the task of choosing a quality publication — that problem had never been known in the era of manuscripts. That was the reason for title pages to appear in books: the name of the printer, his trademark, was placed on the first page, as well as a long title describing and praising the content of the book in order to entice a potential reader. And here we have the first title page in the history of book, in which all the output information is given in poetic form.