Michelangelo
With the completion of the "David" came another commission. In early 1504 Leonardo da Vinci had been commissioned to paint "The Battle of Anghiara" in the council chamber of the Palazzo Vecchio, depicting the battle between Florence and Milan in 1440. Michelangelo was then commissioned to paint the "Battle of Cascina". The two paintings are very different: Leonardo depicts soldiers fighting on horseback, while Michelangelo has soldiers being ambushed as they bathe in the river. Neither work was completed and both were lost forever when the chamber was refurbished. Both works were much admired, and copies remain of them, Leonardo's work having been copied by Rubens and Michelangelo's by Bastiano da Sangallo.
Separation of Light from Darkness
Several authors have proposed that Michelangelo concealed anatomical images in this fresco and that these anatomical images account for its unusual features. In an article published in the journal "Neurosurgery" in May 2010, Ian Suk, a medical illustrator, and Rafael Tamargo, a neurosurgeon, both from the Johns Hopkins University School of Medicine, suggested that Michelangelo concealed three neuroanatomical images in the "Separation of Light from Darkness." Suk and Tamargo explained that Michelangelo started to dissect cadavers at the age of 17–19 years and continued his anatomical studies throughout his life. As a result of his dissections, Michelangelo probably developed a detailed understanding of gross anatomy of the brain and spinal cord. They showed that the anatomical details in God's neck are unlike those of either other necks painted by Michelangelo in the Sistine Chapel or of other necks painted by Michelangelo's contemporaries, such as Leonardo da Vinci and Raffaello Sanzio (Raphael). The unusual anatomy of God's neck is particularly evident when it is contrasted with the anatomy of the neck of the ignudo facing God in the upper left corner of the panel. The position of the neck of this ignudo is almost identical to that of God's neck, yet the ignudo's neck does not have any of the unusual lines found in God's neck. It is possible that Michelangelo placed these two analogous neck perspectives side by side to emphasize and contrast the hidden image in God's neck.