Leonardo da Vinci: Adoration of the Magi, oil on panel, 2.43×2.46 m, c. 1481 (Florence, Galleria degli Uffizi); photo credit: Alinari/Art Resource, NY

Leonardo da Vinci: The Virgin of the Rocks (The Virgin with the Infant Saint John adoring the Infant Christ accompanied by an Angel), panels from the S. Francesco Altarpiece, Milan, oil on wood, 1895×1200 mm, 1491‒1508 (London, National Gallery, bought 1880); © National Gallery, London/Art Resource, NY

Leonardo da Vinci: Portrait of a Lady with an Ermine (Cecilia Gallerani), oil on panel, 534×393 mm, c. 1490–91 (Kraków, Czartoryski Collection); Photo credit: Erich Lessing/Art Resource, NY

Leonardo da Vinci: Last Supper (begun c. 1495), tempera mural, S Maria delle Grazie, Milan; photo credit: Alinari/Art Resource, NY

Leonardo da Vinci: ‘Mona Lisa’, panel, 600×470 mm, c. 1500–07 (Paris, Musée du Louvre); Photo credit: Réunion des Musées Nationaux/Art Resource, NY

Leonardo da Vinci: Head of a Man in Profile Facing to the Left, pen and brown ink, over soft black chalk, 4-5/8 x 2-1/16 in. (11.7 x 5.2 cm), 1490-1494 (New York, Metropolitan Museum of Art, Rogers Fund, 1909, Accession ID:10.45.1); photo © The Metropolitan Museum of Art

Leonardo da Vinci: Studies of the Heads of Shouting Warriors for the Battle of Anghiari (facsimile), black and red chalk, 191×188 mm, c. 1504–5 (Florence, Galleria degli Uffizi, Gabinetto dei Disegni); Photo credit: Scala/Art Resource, NY

Leonardo da Vinci: Embryo in the Womb, pen and ink, 304×215 mmc. 1510 (Windsor Castle, Royal Library); photo credit: HIP/Art Resource, NY

Leonardo da Vinci: Designs for a Nativity or Adoration of the Christ Child; Perspectival Projection, metalpoint partly reworked with pen and dark brown ink on pink prepared paper; lines ruled with metalpoint , 7-5/8 x 6-3/8 in. (19.3 x 16.2 cm), 1480–1485 (New York, Metropolitan Museum of Art, Rogers Fund, 1917, Accession ID:17.142.1); photo © The Metropolitan Museum of Art http://www.metmuseum.org/Collections/search-the-collections/90004535

Leonardo da Vinci: design for a church, pen, brown ink and black chalk, c. 1490 (Paris, Bibliothèque de l’Institut de France); photo credit: Réunion des Musées Nationaux/Art Resource, NY

Peter Paul Rubens: Battle of Anghiari (also called the Battle for the Standard), black chalk, pen and brown ink, heightened with gray white, 452×637 mm, 15th century (Paris, Louvre); © RMN-Grand Palais/Art Resource, NY

Andrea del Verrocchio: Woman Holding Flowers, marble, h. 610 mm, 1475–80 (Florence, Museo Nazionale del Bargello); Photo credit: Scala/Art Resource, NY

Leonardo da Vinci: Head of the Virgin., black chalk, red chalk, traces of white chalk (?); some remains of framing outline in pen and brown ink at upper right (not by Leonardo), 8 x 6-1/8 in. (20.3 x 15.6 cm), 1508-1512 (New York, Metropolitan Museum of Art, Harris Brisbane Dick Fund, 1951, Accession ID:51.90); photo © The Metropolitan Museum of Art http://www.metmuseum.org/Collections/search-the-collections/90004537

Leonardo da Vinci: Virgin and Child with SS Anne and John the Baptist, charcoal heightened with white , 1.41×1.04 m, 1500 (London, National Gallery); photo credit: Art Resource, NY