Agnes Martin suffered from debilitating psychosis: she had visions and heard voices and was hospitalised repeatedly. In 1967 she fled New York, resurfacing around 18 months later on a remote mesa in New Mexico.

But these turbulent personal experiences did not directly shape her quiet, structured compositions. Rather she strived to capture the intangible essence of being — beauty, happiness, innocence, joy.

Painted just one year before her death, Untitled #1 2003 features two opaque triangles that evoke mountainous forms. ‘Nature is like parting a curtain, you go into it,’ she said. ‘I want to draw that quality of response from people, an experience of simple joy.’