How we cite our quotes: (line)
Quote #1
For my first twenty years, since yesterday, (line 1)
The first line of the poem sets up a blatant contradiction: the poem's "metaphysical conceit." The conceit is that while time passes normally for everyone else, it feels really long to the speaker.
Quote #2
Tears drown'd one hundred, and sighs blew out two ; (line 5)
Line 5 is the point at the poem when it becomes obvious that no one could possibly live this long. Time passes faster and faster, which really means that time feels longer and longer for the speaker.
Quote #3
A thousand, I did neither think nor do, (line 6)
Time makes another leap, jumping from the hundreds to the thousands of years.
Quote #4
Yet call not this long life ; (line 9)
The end of the poem anticipates an objection every reader of this poem thinks at some point: impossible. This guy is old enough that he could have been one of Socrates's students in Ancient Greece. The speaker tells us that we have the wrong idea if we think that he is just old.
Quote #5
by being dead, immortal (line 10)
The speaker is not old, because he is dead. To be both "dead" and "immortal" is a total oxymoron, or contradiction in terms. Immortality means that you can't die. To make this contradiction work, the speaker has to fall back on supernatural language: he's a ghost.