Leonardo da Vinci
Studies for Hercules Holding a Club Seen in Frontal View, Male Nude Unsheathing a Sword, and the Movements of Water (Recto); Study for Hercules Holding a Club Seen in Rear View (Verso)
Pen and brown ink; soft black chalk or charcoal (recto); soft black chalk or charcoal (verso), c. 1506-8
Metropolitan Museum of Art, Manhattan, United States