I might be mistaken, but I believe this is the first time that Arthur Schopenhauer has appeared in an adult webcomic. It might be my imagination, but it appears that here a middle-aged Schopenhauer is irritating a young Karl Marx (which I guess could have happened).
(Click on the image for larger size.
Study Abroad: Chapter Five, Page Twenty written and commissioned by Dr. Faustus of EroticMadScience.com and drawn by Lon Ryden is published under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.)