The opening line of the monologue given by Rutger Hauer at the end of Blade Runner. Apparently, the whole thing was ad-libbed, which is surprising given the beauty especially the last two lines. It goes:

I've seen things you people wouldn't believe.
Attack ships on fire off the shoulder of Orion.
I watched C-beams glitter in the dark near the Tannhauser gate.
All those moments will be lost in time, like tears in rain.
Time to die.

It comes at the end of the movie, where Roy Batty, the leader of the Replicants, realises that his fixed length lifetime of four years is just about to end. He then releases a dove, which flies away; then he dies, the rain dripping from his hair.