The Great Gatsby - That damn elusive rhythm

Gatsby recounts to Carraway an evening five years previous which is then assimilated into his 3rd person narrative:

[Gatsby] talked a lot about the past, and I gathered that he wanted to recover something, some idea of himself perhaps, that had gone into loving Daisy. His life had been confused and disordered since then, but if he could once return to a certain starting place and go over it all slowly, he could find out what that thing was...
...One autumn night, five years before, they had been walking down the street when the leaves were falling, and they came to a place where there were no trees and the sidewalk was white with moonlight. They stopped here and turned towards each other...Then he kissed her.

This beautiful romantic reminiscence (not quoted here in full) is then succeeded by the narrator's mental battle to free some profound and incisive memory tantalizingly teased forth:

Through all he said, even through his appalling sentimentality, I was reminded of something - an elusive rhythm, a fragment of lost words, that I had heard somewhere a long time ago. For a moment a phrase tried to take shape in my mouth and my lips parted like a dumb man's, as though there was more struggling upon them than a wisp of startled air. But they made no sound, and what I had almost remembered was uncommunicable for ever. - p71

Again there may be allusions to Eliot's 'Prufrock' as he contemplates: 'Should I, after tea and cakes and ices,/ Have the strength to force the moment to its crisis?'. It is perhaps a magnificent description of that irritating and frustrating sensation of feeling some recollection through indirect association which at the moment of conscious focus evaporates beyond comprehension. Then again, maybe it was nothing... somehow though, I don't think so.