Anatomical study of a fetus in a uterus at four months of gestation (pen over red chalk, circa 1510–1513). Artists use studies in preparation for a finished piece, or as visual notes. Written notes alongside visual images add to the import of the piece as they allow the viewer to share the artist's process of getting to know the subject. Unfortunately notepaper often lacks the quality needed to ensure the study's longevity.Artist: Leonardo da Vinci, photo by Luc Viatour