Now, although Giotto had discovered that, to make you feel that you could walk back through his pictures, he must represent the successive planes, he only partly found out how to do it. It was not until nearly a hundred years later that a painter named Masaccio learned how to fill the whole of his picture with a suggestion of atmosphere, so that the objects took their places properly in their proper planes, and it was still later before artists thoroughly worked out the methods of perspective.