Sudip Bose at The American Scholar:
In 1942, when Levant was back in New York City, he commissioned Schoenberg to write a piano piece for him. Expecting something short, perhaps the length of a Chopin Nocturne, Levant “wasn’t prepared,” as he later wrote, for the full-length concerto upon which the composer instead embarked. Accompanying a letter dated August 8, 1942, Schoenberg sent roughly a quarter of the manuscript to Levant. The work, Schoenberg wrote, would be in four parts and would include a scherzo, an adagio, and a rondo-like finale. But though Levant had already paid an installment of $200, a final fee for the commission had yet to be agreed upon. Schoenberg naturally wanted to finalize the details. What followed was a delicate back and forth, the two artists acting like a pair of uneasy dance partners.
more here.