© Charles Paul Wilp, 1961, Yves Klein, Museum Haus Lange, Krefeld

In the history of invisible art, perhaps the most visible landmark remains Yves Klein’s 1958 exhibition at Galerie Iris Clert in Paris, The Specialization of Sensibility in the Raw Material State into Stabilized Pictorial Sensibility – an empty gallery, apart from a single cabinet, in which every surface had been painted white.

Klein maintained that the space was saturated with a force field so tangible that some people were unable to enter the exhibition “as if an invisible wall prevented them.” Others may have been unable to enter because spectacular press coverage ensured huge queues of spectators searching for something to look at. (+)