Yves Klein, born in Nice in 1928, was throughout his life determined to find a vessel for a 'spiritual' pictorial space, and it was this that led him eventually to live actions. To Klein, painting was 'like the window of a prison, where the lines, contours, forms and composition are determined by the bars'.

Monochrome paintings, begun around 1955, freed him from such con­straints. Later, he said, he remembered the colour blue, 'the blue of the sky in Nice that was at the origin of my career as a monochromist' and at an exhibition in Milan in January 1957, he showed work entirely from what he called his 'blue period', having searched, as he said, 'for the most perfect expression of blue for more than a year'. In May of the same year, he had a double exhibition in Paris, one at the Galerie Iris Clert (10 May) and the other at the Galerie Colette Allendy (14 May). The invitation card announcing both exhibitions displayed Klein's own International Klein Blue monogram. For the Clert opening he presented his first Aerostatic Sculpture, composed of 1001 blue balloons released 'into the sky of Saint Germain-des-Pres, never to return', marking the beginning of his 'pneumatic period'. Blue paintings were exhibited in the gallery, accompanied by Pierre Henry's first taped version of the Symplionie Monotone. In the garden of the Galerie Colette Allendy he showed his One Minute Fire Painting, composed of a blue panel into which were set sixteen firecrackers which produced brilliant blue flames.

It was at this time that Klein wrote 'my paintings are now invisible' and his work The Surfaces and Volumes of Invisible Pictorial Sensibility, exhibited in one of the rooms at the Allendy, was precisely that; invisible. It consisted of a completely empty space. In April 1958, he presented another invisible work at the Clert, known as Le Vide ('The Void'). This time the empty white space was contrasted with his inimitable blue, painted on the exterior of the gallery and on the canopy at the entrance. According to Klein the empty space 'was crammed with a blue sensibility within the frame of the white walls of the gallery'. While the physical blue, he explained, had been left at the door, outside, in the street, 'the real blue was inside . . .'. Among the three thousand people who attended was Albert Camus, who signed the gallery visitors' book with 'avec le vide, les pleins pouvoirs' ('with the void, a free hand').

Klein's Blue Revolution and Theatre du vide were given full coverage in his four-page newspaper Le Journal d'un seul jour, Dimanche (27 November 1960), which closely resembled the Paris newspaper Dimanche. It showed a photograph of Klein leaping into the void. For Klein, art was a view of life, not simply a painter with a brush in a studio. All his actions protested against that limiting image of the artist. If colours 'are the real dwellers of space' and 'the void' the colour of blue, his argument went, then the artist may just as well abandon the inevitable palette, brush and artist's model in a studio. In this context, the model became 'the effective atmosphere of the flesh itself'.

Working with somewhat bemused models Klein realised that he did not have to paint from models at all, but could paint with them. So he emptied his studio of paintings and rolled the nude models in his perfect blue paint, requesting that they press their paint-drenched bodies against the prepared canvases. 'They became living brushes ... at my direction the flesh itself applied the colour to the surface and with perfect exactness.' He was delighted that these monochromes were created from 'immediate exper­ience' and also by the fact that he 'stayed clean, no longer dirtied with colour', unlike the paint-smeared women. 'The work finished itself there in front of me with the complete collaboration of the model. And I could salute its birth into the tangible world in a fitting manner, in evening dress.' It was in evening dress that he presented this work, entitled The Anthropometries of the Blue Period, at Robert Godet's in Paris in the spring of 1958, and publicly at the Galerie Internationale d'Art Contemporain in Paris on 9 March 1960, accompanied by an orchestra also in full evening dress, playing the Symphonie Monotone.

Klein considered these demonstrations as a means to 'tear down the temple veil of the studio ... to keep nothing of my process hidden'; they were 'spiritual marks of captured moments'. The International Klein Blue of his 'paintings' was, he said, an expression of this spirit. Moreover, Klein sought a way to evaluate his 'immaterial pictorial sensitivity' and decided that pure gold would be a fair exchange. He offered to sell it to any person willing to purchase such an extraordinary, if intangible, commodity, in exchange for gold leaf. Several 'sales ceremonies' were conducted: one took place on the banks of the River Seine on 10 February 1962. Gold leaf and a receipt changed hands between the artist and the purchaser. But since 'immaterial sensitivity' could be nothing but a spiritual quality, Klein insisted that all remains of the transaction be destroyed: he threw the gold leaf into the river and requested that the purchaser burn the receipt. There were seven purchasers in all.

From the book "Performance Art" by RoseLee Goldberg, Thames and Hudson, London, 1988

[Yves Klein (April 28, 1928, Nice, France - June 6, 1962, Paris, France) lived in Japan for a time, becoming an expert in judo. By the late 1950s, his monochrome works were almost exclusively in a deep blue hue which he eventually patented as International Klein Blue. Klein is considered an important figure in post-war European neo-Dadaism. He engaged in such provocations as "publishing" a chapbook containing only empty pages and selling empty spaces in exchange for gold which he then threw into the river Seine.]