"I had left the visible, physical blue at the door, outside, in the street. The real blue was inside, the blue of the profundity of space, the blue of my kingdom, of our kingdom!. ..the immaterialisation of blue, the coloured space that can not be seen but which we impregnate ourselves with.. .A space of blue sensibility within the frame of the white walls of the gallery."

“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.”