Rothko Returns

In the 1950s, Mark Rothko won the “most prestigious public commission that had ever been awarded to an abstract expressionist painter” to produce “600 square feet of paintings for the most exclusive room in the new Four Seasons restaurant at the Seagram Building in New York.” But in 1959 he “suddenly and unexpectedly repudiated his agreement” and in the 1960s sent nine of the paintings to the Tate in London. Why?