This is an illustration from German painter and printmaker Albrecht Dürer’s Institutionum Geometricarum, a volume on geometry which applies the mathematical theories of Ptolemy and Euclid to drawing, architecture and typography. Plate 61 is taken from book 3 which is dedicated to modifying proportions, including with the use of mirrors and camera obscura. This treatise on the principles of geometry is part of Dürer’s theoretical legacy but also includes some of his most iconic engravings.