In 1538 Vesalius issued two complementary works for students, Tabulae sex anatomicae (Six Anatomical Plates) and the Institutionum anatomicae secundum Galeni sententiam libri quatuor (Principles of Anatomy according to the Opinion of Galen). The former is well known, the latter almost entirely neglected until recently. Together they show the rapid development of Vesalius’s ideas on the body as well as his own abilities as a dissector and artist. He was unusual in his appreciation of what the printing press could offer: the multiplication of images and the possibilities for revision. Newly discovered notes by Vesalius also show him changing his mind about a new edition of the Principles of Anatomy and moving toward a very different anatomical treatise.