To create this work, Spencer Finch precisely recorded the quality of light at the transition point between the shadowy interior and entrance of Lascaux Cave, discovered in 1940 in south-west France, which contains extraordinary examples of prehistoric art. In the gallery space, Finch recreates this light with fluorescent tubes and calibrated colour filters. The angle of the tubes mirrors the angle of a mountain as seen across the valley from the cave entrance, while the colours relate to pigments in the cave's prehistoric paintings, as well as tones from the landscape and sky outside.