A century after his birth, on Jan. 24, 1915, Robert Motherwell occupies a middle rung on the reputation ladder of Abstract Expressionists. The names Jackson Pollock, Mark Rothko, Willem de Kooning, Barnett Newman, Clyfford Still and possibly others would now come sooner to many people’s minds on the topic.

But through the long arc and productive prime of his career, Motherwell was as important as anyone in shaping the transformative artistic mode of the mid-20th century.