 Bacon 's output is characterised by sequences of images . He told Sylvester that his imagination was stimulated by sequences and that " images breed other images in me " . His series were not always planned or painted in sequence ; sometimes paintings are grouped for convenience but vary in execution and tone . The idea for the head series came after he returned penniless , late in 1948 , from a stay in Tangier . In the previous three years he had been unable to find a voice ; the last surviving canvas from this period is his Painting ( 1946 ) . Although he continued to paint , he was a ruthless self critic , given to slashing canvases with blades , and no works survive from between 1947 and the winter of 1948 . <unk> Erica <unk> offered Bacon the opportunity of a solo show for the opening of her new Hanover Gallery . He agreed , but had nothing in reserve to hang . In following years , <unk> became perhaps the most important of Bacon 's early champions ; she arranged this showing — his debut solo exhibition — publicised him widely and organised viewings for international buyers . 
