There's also that processional bass line in the minor which goes tonic, third, tonic up the octave, third, lower tonic again. He uses that a heck of a lot - Reiner do you know Dernier Poème?
That one is from Symphony of Psalms...
See also 1st mt of Oboe Sonata. (Mart, agreed, it's the best of the wind sonatas - more flautists should play it!
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Reiner - I must check out which piano piece you are referring to - there are no preludes, as far as I know. Ollie, the Flute Sonata was written at about the same time as Carmelites and I always think of that last movement as a futile attempt to escape from deep depression (which he had when writing the opera) by throwing oneself into some useless activity - so maybe some subconscious 'inescapable fate motif' ?
I'm always puzzled by the Gloria quote in the 1st mt of the clarinet sonata.
Here's another pic - he looks cheerful here, but you can see he has a screw loose...