Quicksand

This song is both existetialist and Thelemic. I also agree with Stairwaytoheaven's idea of the songwriter's cyclical thought process. This song describes Bowie's wrestling with new Thelemic ideas and reconciling them with his past beliefs.

The entire first stanza referrs blantantly to Crowley and the horror of the final goal of Thelemic teaching: to remove all shred of one's ego and reduce the psyche to first hyperawareness, then unawareness, then re-awareness, through a process referred to only as "crossing the Abyss". This is a process not unlike descent into schitzophrenia (and indeed, some Thelemites have been reported as having attempted the final goal and gone insane instead) and it's completely understandable why he would be frightened by it.

The idea of "a mortal with potential of a superman" is totally Thelemic. Thelemites believe every man and woman can become a god, if they are able to properly discipline their minds and cross the Abyss.

The chorus (or refrain, I suppose) seems to be a sort of counterpoint to this thinking. He is telling himself not to worry about it so much, that things will work out after death. But he continues to contemplate, and worry about the state and potential of his soul, and the cycle continues. Thus he's sinking in the quicksand of his thought, piling the concepts onto his mind, churning them until he can barely hold his head above the surface.