How we cite our quotes: I cite by line number only.
Quote #1
O what can ail thee, knight at arms,
Alone and palely loitering? (lines 1-2)
The opening image of the poem is the knight looking "pale" and "ail[ing]" while hanging out "alone." Clearly, this guy doesn't want to be alone. Even that opening syllable, "O" suggests emptiness (it looks like a zero).