Oliva Laing profiles painter Agnes Martin. An exhibition of Martin's work will be on view at Tate Modern from June 3 – October 11, 2015.

Laing begins "Art must derive from inspiration, Agnes Martin said, and yet for decades she painted what seems at first glance to be the same thing over and over again, the same core structure subject to infinitely subtle variations. A grid: a set of horizontal and vertical lines drawn meticulously with a ruler and pencil on canvases six feet high and six feet wide. They came, these restrained, reserved, exquisite paintings, as visions, for which she would wait sometimes for weeks on end, rocking in her chair, steadying herself for a glimpse of the minute image that she would paint next. 'I paint with my back to the world,' she declared, and what she wanted to catch in her rigorous nets was not material existence, the Earth and its myriad forms, but rather the abstract glories of being: joy, beauty, innocence; happiness itself."