Well contrary to first assumptions, it is the winter and not the summer soltice that is the symbol of 'light'. For most civilisations the winter solstice was celebrated as the time when the saviour/avatar/divine being would be born into the world to lift it out of the 'darkness' - both literally bringing it from winter into spring/summer and symbolically bringing light and order out of the dark chaos. It is the 'ascent' phase of the year:
http://belsebuub.com/articles/the-spiritual-meaning-of-the-winter-solstice
I doubt Simon was considering any of these things tbh.
As for the song itself, this version is decent but has nothing on the album version which is far more coherent and tight, not to mention has some of his greatest moments. This is something like a beta version - you can see the framework for the final song, but its really all over the place:
Intro: the only thing I hate about the album version - cheesey flute sound (despite him speeding it up for the album). Unfortunately for this verison, he continues it throughout the song.
0:33: interesting little melody here that would be good to see hium play around with - not on album version
1:04: cheese back. Not saved by the LSD type melody brought in at 1:18
2:00 lol at that sample. Stupid but funny.
2:19 cool 'spacey' soundscape that he reworks for the album
2:35 brings back cool melody over spacey sound - best section of the song... until
3:17 that bizarre 80's keyboard sound is horrid; thank god he dropped it for album version
3:30 the main chorus from album version, but here it has no build-up and thus loses most of its impact
3:45 transition/bridge from album version
4:00 goddam cheese back
4:45-end is mixing all previous inputs and wind down.
In summary, the album version is far more polished, loses all the weaker parts of this version (except that flute!), and adds some of Simon's most powerful moments.
I also really like his killer remix of Solstice for the dancefloor (a lot more acid) in his live @ DNA lounge set (7:10):
