The many suns may set and rise as usual. But after this brief light of ours is snuffed, We have a single night to sleep for ever.
What moves me in this poem is not the bleak rejection of an afterlife, but the sudden flash of insight that comes from feeling one day turning after another. This is the analeptic memory Graves spoke of: the future, as the past, compressed in a single blinding instant of awareness; the "many suns" frozen in a searing trace fixed in the sky, the short stub of a candle that will not be enough to see us through the night.
This is enlightenment, too.