What is the last name of the person who often approached a canvas without having a clear idea of what might emerge?  Answer the above question based on the context below:  The paintings depict isolated figures enclosed in spaces that are undefined, overwhelmingly claustrophobic, reductive and eerie. Coming early in Bacon's career, they are uneven in quality, but show a clear progression especially in how they utilise and present ideas he was still clearly developing and coming to terms with. Head I (actually begun in the winter of 1948) and Head II show formless pieces of flesh that broadly resemble human heads; they have half-open eyes and a pharynx, though it is positioned much higher than would be expected in a human. Heads III, IV and V show fully formed busts recognisable as men, and are characterised by a haunted atmosphere. These two broad ideas coalesce in Head VI, which is as physiologically tortured as the first two paintings, and as spectral as the middle three. In Head VI the figure has developed and is now shown wearing vestments, the first indication in Bacon's work of the influence of Velázquez, while the focus has become the open mouth and the study of the human scream.Bacon said that chance played a significant role in his work, and that he often approached a canvas without having a clear idea of what might emerge. This was especially the case in the mid- to late 1940s, a period when he was drinking heavily and spending most nights in Soho casinos and poker rooms. The following morning he would often approach his canvas "in a bad mood of drinking ... under tremendous hangovers and drink; I sometimes hardly knew what I was doing." He incorporated his appetite for chance into his work: an image often would morph midway through into something quite different from what he had first intended. He actively sought out this freedom and felt it crucial to his progression as an artist. To him, lifestyle and art were intertwined; he said that "perhaps the drink helped me to be a bit freer." This is very evident in the 1949 series, which began as a rather morbid study of a collapsed head, but evolved over the six surviving panels into a reworking of Velázquez masterpieces,...
A:
Bacon