"Blue has no dimensions, it is beyond dimensions, whereas the other colours are not. They are pre-psychological expanses, red, for example, presupposing a site radiating heat.. .All colours arouse specific associative ideas, psychologically material or tangible, while blue suggests at most the sea and sky, and they, after all, are in actual, visible nature what is most abstract."

“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?”

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

“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.”

“I am against the line and all its consequences: contours, forms, composition. All paintings of whatever sort, figuratives or abstract, seem to me like prison windows in which the lines, precisely are the bars.”