As an apprentice printmaker, José Guadalupe Posada learned the techniques of lithography and engraving on wood and metal. Posada went on to produce an estimated twenty thousand works over the course of his life. His subject matter included natural disasters, the miraculous and the macabre, and satirical commentary concerning politics, the common people, and revolution (which occurred during his lifetime). The best-known vehicles for his satire are his calaveras (skulls) inspired by the skeletal figures used to celebrate of Mexico’s Day of the Dead holiday.