Alas! that all we lov'd of him should be, But for our grief, as if it had not been, And grief itself be mortal! Woe is me! Whence are we, and why are we? of what scene The actors or spectators? Great and mean Meet mass'd in death, who lends what life must borrow. As long as skies are blue, and fields are green, Evening must usher night, night urge the morrow, Month follow month with woe, and year wake year to sorrow.
It's sad, the speaker says, that our grief over Adonais-Keats is really the only thing keeping the things we love about him from ceasing to exist.
Even then, he says, grief itself is mortal; it dies too, in its way. We won't be grieving forever, which means the things we love about the youth will eventually fade away.
This leads him to wonder where ("whence") we come from, and why. We guess this death has had a pretty profound effect on the speaker; he's questioning the very purpose of life.
He wants to know: are we actors, or spectators? In the end, he says, the little people and the more "important" ("great") people all wind up in the same place. This will never change, not as long as the skies are blue, etc. It's the way the world works.
Notice even more tongue-twisting lines as Shelley plays with words and sounds in this stanza ("year wake year")? Check out our "Sound Check" section for the lowdown.