Four Books on Human Proportion (1528) - Page 1

[Image: The monogram of Albrecht Dürer]

The page is dominated by a large, stylized letter A, characterized by a horizontal bar across its top and serifs at its feet. Nested within the open space at the bottom of the A is a smaller, cleanly drawn letter D.

This "AD" insignia is the world-renowned monogram of Albrecht Dürer (1471–1528), the most influential artist of the German Renaissance. His signature was one of the first "brand logos" in art history, used to protect his woodcuts and engravings from unauthorized copies.