it just sounds so beautifully yet tragicially messed up - shows the full depth of his obsessions with Occult mysticall thinking and beliefs bordering on Fascism, and the way he sings "Knowledge comes with death’s release" and the total resignation of "I’m sinking in the quicksand of my thought And I ain’t got the power anymore Don’t believe in yourself"
It is indeed a sad song but I think some of the songs "Man Who Sold The World" are sadder, before he went through the ziggy stardust transformation.