Why was the title page in Regiomontanus’s Calendarium important to book design?

The title page of Regiomontanus’s Calendarium, printed in 1476, is significant to the history of book design because it was the first complete printed title page.1

Unlike earlier versions of title pages, which functioned primarily as half titles, this design established a new standard by identifying the book's title, author, printer, and date of publication. This development marked a transition in the evolution of the typographic book, as the title page began to absorb information previously contained in the colophon.21

Beyond its functional role in providing a protective cover for the text, the title page served as an important tool for advertising the work and the publisher-printer. By the end of the incunabula period (1450–1500), this device had become well-established, helping to define the modern design vocabulary of the printed book.21