Opera medica.
Opera medica is a medical treatise by Antonio Guainerio, died 1440, printed in 1500, for physicians and medical practitioners. The first picture is a Yale Medical Library Historical Library bookplate from the Harvey Cushing Fund, a scan artifact rather than part of the book, while the second is a woodcut printer's device of a cross over a circle with a monogram, set in a black field with a thin border, showing how early printers marked their pages with compact emblematic symbols a designer could adapt for a logo or seal.
