Context

You're looking at the opening stanza of Dylan Thomas's most famous poem, "Do Not Go Gentle into That Good Night." 

It's a villanelle, so we should be prepared for the repetition of the first and third line throughout the poem, along with the continuing rhyme scheme. As we'll see in the final stanza, the poem addresses Dylan's father who, when Dylan wrote this, was going blind and dying.

Did we mention it's a downer?

If you haven't figured it out, night is death (and, more literally, the blindness that comes with old age), and the speaker is telling us to not go quietly, but to strive to live so that we can go out with a bang.

Where you've heard it

You might just know it as "that one poem from Interstellar."

Pretentious Factor

If you were to drop this quote at a dinner party, would you get an in-unison "awww" or would everyone roll their eyes and never invite you back? Here it is, on a scale of 1-10.

Sure, you're quoting poetry, but it's about maintaining purpose in life and continuing to make a mark on the world. We can get behind that.