The position of Sapa Inca was hereditary, which means that it passed from father to son. The Sapa Inca was the sole and absolute ruler over the Incas. His word was law, and he was the supreme commander of the military. The Sapa Inca lived in great luxury with many wives, slaves, and riches. Another privilege that he had was that he was allowed to (and usually would) marry his sister even though it was prohibited for common people. When the Sapa Inca died he would be mummified.