Which artist believed that a living figure was concealed in block of marble and only the excess needed to be carved away reveal it?

The artist who believed that a living figure was concealed in a block of marble and only the excess needed to be carved away to reveal it was Michelangelo.

This belief is known as the "theory of the blocco" and it is often associated with his famous quote: "Every block of stone has a statue inside it and it is the task of the sculptor to discover it."