True or false ? Erinnerung an die Marie A

"An jenem Tag im blauen Mond September
Still unter einem jungen Pflaumenbaum
Da hielt ich sie, die stille bleiche Liebe
In meinem Arm wie einen holden Traum!".
 
One day in 1920, Bertolt Brecht happened to be on a train to Berlin and jotted down the words of this poem.  The song, which fits a n old popular tune, has become one of Brecht's "greatest hits". There have been many attempts to explain it. Is it autobiographical?  Is it literary? Or is it one of those things that just pop into one's mind from the unconscious?  Plum trees don't blossom in September, at least not in Germany.  Perhaps seeing a random cloud jogged the memory. Once the poet embraced a woman under a blossong plum tree. He's forgotten the woman's face, and doesn't remember what happened to her  Perhaps the "Frau hat jetzt vielleicht das siebte Kind". Having seven children suggests the end of romance and adventure - perhaps the girl is now hardened and worn, youth vanished, like the cloud the poet glimpsed when his mind should have been on other things. Perhaps the trees have since been chopped down. Clouds are ephemreal: ever changing, transient. As are our lives.

 "Doch jene Wolke blühte nur Minuten
Und als ich aufsah, schwand sie schon im Wind".