"Untitled (Brown and Gray)" by Mark Rothko, 1969

Rothko started his Brown and Gray series in late 1968. On medical advice following an aortic aneurysm earlier that year, he limited himself to canvases no more than 40 inches. No doubt his doctors intended him to paint less strenuously, but instead of painting huge canvases Rothko created loads of smaller works on paper. His studio assistants taped sheets of paper to wooden boards; when Rothko was finished the tape was removed to create an unpainted paper edge to the work.