A bill for 20 grams of Pure Gold, for one painted area of sensibilized immaterial. [about 1958, text on a bill for selling 'air'] - Yves Klein

It was in 1947 that the idea of a conscious monochrome vision came to me.. .Pure, existential space was regularly winking at me, each time in a more impressive manner, and this sensation of total freedom attracted me so powerfully that I painted some monochrome surfaces just to 'see', to 'see' with my own eyes what existential sensibility granted me; absolute freedom! But each time I could neither imagine or think of the possibility of considering this as a painting, a picture, until the day when I said: Why not?

In case the buyer wishes this act of integration of the work of art with himself to take place, Yves Klein must.. ..plus two witness, throw half of the gold received in the ocean, into a river or in some place of nature where this gold cannot be retrieved by anyone. From this moment on, the immaterial pictorial sensitivity zone belongs to the buyer absolutely and intrinsically.

I want to take as the canvas for my next picture the entire surface of France. This picture will be called 'The Blue Revolution'. It isn’t the fact of my taking power in France that interests me, but rather the possibility of creating a monochrome picture in my new manner: ‘The Refinement of Sensibility’.