Andy Warhol (1928-1987) is arguably the most influential artist of the last half of the 20th century, in large part because his flat images communicate so effectively. There are no details, no individual brushwork, to get hung up on. Warhol exploits the simultaneously empty and mysterious icons of pop culture and reproduces existing images – from Campbell’s soup cans to Jackie Kennedy, Chairman Mao and Coca-Cola bottles. The artistic execution provides no insight into the artist’s interiority. They are about the world outside the pictures.

The career of the French artist Yves Klein (1928-1962) was as intense as it was brief, lasting essentially from 1956 to 1962. Klein’s art introduces us to two central and conflicting movements: action and immense calm. This calm radiates from the monochrome canvases, but also very much from the effect they have. We search the three monochrome surfaces for action and direction, but there is none. Even when Klein rolls paint-covered bodies on the canvas or burns his paintings with flamethrowers, he controls every movement. Contemplation and action tie his intense and richly coloured works together, like two doors leading to the same place.