His speed of execution very quickly became his signature style. In 1959 he painted the 2.5x6 metre painting "Le Massacre de la Saint-Barthélemy" (The Saint-Bartholomew's Day Massacre) in less than half an hour, accompanied by the jazz drummer Kenny Clarke. "I did not paint fast by lack of time or to break records, but simply because I did not need more time to do what I had to do and conversely, a longer time would have slowed down gesture, introducing doubts, would have affected the purity of strokes, the cruelty of shapes, the unity of the artwork."