Xenocrates — By Gottlieb Friedrich Riedel (1724–1784) - Originally from the book Gallerie der alten Griechen und Römer sammt einer kurzen Geschichte ihres Lebens. Band 1: Philosophen by Georg Wilhelm Zapf, published in Augsburg by Gottlieb Friedrich Riedel in 1781, illustration of Xenocrates between pages 26 and 27. A second edition of the book was published in 1801. File taken from the digital version at http://diglit.ub.uni-heidelberg.de/diglit/zapf1781
Photo Credit: Public Domain, https://commons.wikimedia.org/w/index.php?curid=361188