"Through all these researches into an art that would lead to immaterialisation, Werner Ruhnau and I came together in the architecture of the air. He was hindered by the last obstacle that even a w:Mies van der Rohe hadn’t been able to overcome: the roof, the screen that separates us from the sky, from the blue sky. And I was hindered by the screen that the tangible blue on the canvas constitutes, which deprives man of a constant vision of the horizon."

“detailed biography of Yves Klein”

“This period of blue monochrome was the product of my pursuit of the indefinable in painting which that master, Eugène Delacroix was able to indicate even in his day.”

“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 1946, when I was still an adolescent, I went and signed my name on the other side of the sky during a fantastic 'realistico-imaginary' voyage.”

“A bill for 20 grams of Pure Gold, for one painted area of sensibilized immaterial.”

“Dubbed as a Knight of the Order of Saint Sebastian, I espoused the cause of pure colour, which has been invaded by guile, occupied and oppressed in cowardly fashion by line and its manifestation; drawing in Art. I aimed to defend and deliver it, and lead it to triumph and final glory.”