Agnes Martin's paintings of austere graphite grids and subtle bands of color grew out of a pressing need to express what the artist called "the most simple, powerful things." Her breakthrough came in the mid-1960s with a series of simple pencil grids ruled directly onto gessoed canvases, of which the Modern's "Leaf," 1965, is a classic example. Throughout the 1970s, Martin began opening up her grids, emphasizing the intervals between the lines and creating different sensations of space and atmos

Ever wondered how Agnes Martin balanced perfection and imperfection in her gridded compositions, why Jackson Pollock was dubbed “Jack the Dripper,” how Mark Rothko sought to make viewers cry, or what a Willem de Kooning painting sounds like? Sign up for “In the Studio: Postwar Abstract Painting,” MoMA’s newest free online course—now open for enrollment at mo.ma/coursera. This course welcomes anyone to tap into the processes, materials, and minds of seven New York School artists including Martin,