How we cite our quotes:
Yet all experience is an arch wherethrough
Gleams that untravelled world whose margin fades
Forever and forever when I move (19-21)
The "untravelled world" could be a reference to death; when Ulysses "moves," when he travels or lives life to the fullest, he is able to make death seem farther away, less important. Living life – moving – is a way to postpone one's death; maybe not literally, but at least it feels like it.
How dull it is to pause, to make an end,
To rust unburnished, not to shine in use!
As though to breathe were life! (22-24)
Ulysses redefines life as something other than just breathing. Actually, he implicitly suggests that if one only breathes, one is figuratively dead, as he is in Ithaca. For Ulysses, "to make an end," to stop moving, is another version of the "just breathing" hypothesis; it too is a kind of death where one has the ability to "shine" but doesn't.
To sail beyond the sunset, and the baths
Of all western stars, until I die (59-60).
Ulysses wants to sail around the world, even it kills him. So much is clear. But the phrase "until I die" is interesting. On the one hand, it could mean that once he sails beyond the sunset he'll die, or it could mean that he wants to pass "beyond the sunset" and keep on going until his life runs out. The distinction is important, and might suggest that Ulysses has a stronger death-wish than we anticipated.