Apollo granted her wish for as many years of life as grains of sand she could hold in her hand for a promise to sleep with him. When she did not, he gave her eternal life without eternal youth, and she was eventually so withered that she was kept in a jar. As a very old woman, she offered nine of her books to the Roman king Tarquin, who only purchased the remaining three after she burned six. For 
Apollo granted her wish for as many years of life as grains of sand she could hold in her hand for a promise to sleep with him. When she did not, he gave her eternal life without eternal youth, and she was eventually so withered that she was kept in a jar. As a very old woman, she offered nine of her books to the Roman king Tarquin, who only purchased the remaining three after she burned six. For ten points, name this prophetess, the subject of a 1510 painting by Michelangelo.
Apollo granted her wish for as many years of life as grains of sand she could hold in her hand for a promise to sleep with him.
{Cumaean Sibyl} or {Sibyl of Cumae}