"Sponge sculptures – It was also on this occasion that I discovered sponges. While working on my paintings in my studio, I sometimes used sponges. Evidently, they very quickly turned blue! One day I perceived the beauty of blue in the sponge; this working tool all of a sudden became a primary medium for me. The sponge has that extraordinary capacity to absorb and become impregnated with whatever fluid, which was naturally very seductive to me. Thanks to the natural and living matter of sponges, I was able to make portraits of the readers of my monochromes, which, after having seen and traveled into the blue of my paintings, returned from them completely impregnated with sensibility, just as the sponges."
Extract from "Notes on Certain Works Exhibited at the Colette Allendy Gallery", in Yves Klein, Overcoming the Problems of Art: The Writings of Yves Klein, Spring Publications, New York, 2007, p. 22