Yves Klein (1928-1962) shines like a meteor in the sky of twentieth-century art. After his untimely death, there is nothing like it used to be. He is one of the great inspirers of modern art. In 1947, just 19, he signed the sky of Nice, his hometown. The symbolic gesture is an act of appropriation. With the signature of the sky, Klein invites us to a journey of ideas and becomes the pioneer of the most important designers of the sixties and seventies. At the same time, he also moves the boundaries of his studio, which becomes identical to the world for him. He lets nature - rain, sun and snow - contribute to the physiognomy of his paintings.