While abstract artists rejected the idea that art needed to be figurative to be beautiful, they still all used forms and shapes of some sort.
Klein went one step further.
He rejected the idea that an artist needed shapes altogether - and focused instead on the intrinsic power of colour.
Klein believed that beauty already existed in the world - his role as an artist was to identify and share it.
He wanted to "free colour from the carcan of form or shape" and "make the absolute visible".
Fun fact : for his first exhibition, Klein showed monochromes in various colours.
However the audience kept comparing the paintings to each other - which he didn't want.
So his next exhibition featured 11 identical blue paintings, each priced differently.
He decided to stick to this colour and named it IKB - International Klein Blue.
Klein applied this color to various formats - canvasses, sculptures, sponges, and more.
He also involved others in the creation process.
In some works, naked models would cover themselves in IKB and brush against the canvas, using their bodies as paintbrushes.
Klein's IKB paintings have become iconic.
One recently sold for $22 million.