More haunting still, and I think this comes through in the origional recording, was that after not seeing Syd for quite some time he walked into the studio while they were recording this, of all songs.
There is often an underlying theme of insanity and remorse of loss as well as a profound honoring of the past that is seen in many of the works of Pink Floyd. Probably why these tunes strike us so deeply. And will be around for as long as mankind recognizes these aspects of humanity.