The song Octopus by Syd Barrett (originally recorded as "Clowns and Jugglers" and "The Madcap Laughs") is thought to describe his level of insanity among other things. It shows that he is on the brink of going mad, but there is a part of him that is completely mad already.
Syd Barrett was a British singer, songwriter, and musician during the 1960s. He was one of the co-founders of the rock band Pink Floyd in 1965. Barrett was their original frontman and primary songwriter, becoming known for his style of psychedelic rock and stream-of-consciousness writing. Barrett was musically active for less than ten years and was primarily a painter.