These lines are the first which begin to delve into the poem's greater contextual themes which explore infinity and endlessness, as it calls to mind a notion of universality across everything. The infinite and the endless are very similar, but remain distinct: 'infinite' refers to an indeterminable end or countlessness of size; whereas 'endlessness' is the absence of an end. The repetition of "all" (and the repeated moments throughout the poem) is so pertinent here because its repeated flow provides the reader with a sense of "give-and-take", much like a wave - which are then described immediately in the subsequent line/stanza with "Distant ocean-engines". There's a discovered oneness within the dichotomies of "give-and-take", "the comes and goes" the sky ("a water-ceiling") and the subterranean ("underearth plateaus"[which is a seemingly contradictory description of itself]); which makes one question the line between contradiction and balance. There is a oneness and balance present amidst all which seems to contradict, which is why I think mathematics is so especially relevant to the poem's overall theme (of course, outside of the fact of it being Archimedes' field of study). Mathematics is centered around unity: positive vs negative, integral vs differential, rational vs irrational, etc. And once contradiction (which scares us) can begin to become interpreted as balance, the inescapable infinities and endlessness of the universe do become peaceful, like a lullaby.