While improvising at the piano, Elgar came up with a tune that inspired a slew of variations depicting his friends, all attempts to write in their voices.

He also added a mysterious “Enigma” theme that has never been identified.

Pianist Conrad Tao takes on Tchaikovsky’s Piano Concerto, the work the composer valued above all his other piano compositions. The concert, conducted by Nicholas Collon in his SF Symphony debut, opens with Thomas Adès’ vivid Three-piece Suite from Powder Her Face.

// Nov. 7-9 at Davies Symphony Hall, 201 Van Ness Ave. (Civic Center); tickets are available at sfsymphony.org.