Leonardo da Vinci was the first creative thinker who talked and wrote about the importance of introducing random and chance events to produce variation in his thinking patterns. Almost with apology, since it seemed so obvious to him, he advised people to contemplate the walls, clouds, pavements, etc., with the idea of looking for patterns and images to conceptually blend with your thoughts.
Leonardo da Vinci wrote how he got his creative inspiration in his notebooks in a mirror-image reversed script “secret” handwriting which he taught himself. To read his handwriting, you have to use a mirror. It was his way of protecting his thinking strategy from prying eyes. He suggested that you will find inspiration for marvelous ideas if you look for random subjects to conceptually blend with your challenge. He would gaze at the stains of walls, or ashes of a fire, or the shape of clouds or patterns in mud or in similar places. He would imagine seeing trees, battles, landscapes, figures with lively movements, etc., and then excite his mind by conceptually blending the subjects and events he imagined and his subject. Da Vinci would occasionally throw a paint-filled sponge against the wall and contemplate the random stains and what they might represent. – See more at: http://creativethinking.net/articles/2012/03/19/how-leonardo-da-vinci-got-his-ideas/#sthash.xjdm3505.dpuf