Elizabeth Sprague Coolidge (1864–1953) was an American pianist and philanthropist, notable for her sponsorship of chamber music and for commissioning compositions from contemporary composers in the United States and abroad. She established the Elizabeth Sprague Coolidge Foundation, in partnership with the Library of Congress, in 1925 to promote and advance chamber music through commissions and public concerts. In 1925 she also helped finance construction of the Coolidge Auditorium in the Jefferson Building of the Library of Congress to provide a venue for the performance of chamber music. RK played in this auditorium numerous times, as soloist and with the violinist Alexander Schneider and others. As is clear from the letters, Mrs. Coolidge also provided support to RK for concerts in Cambridge, Massachusetts, and elsewhere.

August 19, 1942

Dear Mrs. Coolidge,

Your letter finally arrived this morning. Let me say again how pleased I am at the prospect of our first performance of the Bach under such sympathetic auspices.

Mr. Schneider has just come and I have been talking with him about our plans. We are consulting Mr. Spivacke about possible performance dates in relation to our respective commitments. We feel that we could perfectly well confine ourselves for the present to the six sonatas in two programs.

We thought of five hundred dollars as a suitable fee for each concert, inclusive of the expenses in connection with the harpsichord. I think it would be excellent to broadcast the concerts if possible.

It would give me great pleasure to have the first performance at Harvard, sometime while you are in Cambridge, probably in October or November.

I think I told you the other night how well it made us feel to see you in the front row. Whatever the arrangements about dates, we must be able surely to look forward to that this time. As soon as our rehearsal schedule is final, I will let you know.