Today anyone who paints space must actually go into space to paint [the Russian cosmonaut Gagarin said on 12 April 1961 from his space capsule: 'The earthy is a beautiful blue colour'], but he must there go without any faking, and neither in an aeroplane, a parachute nor a rocket; he must go there by his own means, an autonomous, individual force; in a word, he must be capable of levitating.

In 1961; p. 67 - "Yves Klein, 1928 – 1962, Selected Writings"