“As long as there's life, there's hope.”

Epistulae ad Atticum (Letters to Atticus) Book IX, Letter X, section 3
Often paraphrased as: Dum anima est, spes est ("While there is life there is hope")
Compare: "While there's life there's hope, and only the dead have none." Theocritus, Idyll 4, line 42; as translated A. S. F. Gow
Original: (la) Aegroto dum anima est, spes esse dicitur.

2000s and attributed from posthumous publications
Context: I've been saying for a long time that I'm hoping to find intelligent life in Washington … I'm reasonably sure there must be life in this solar system, on Mars or on Europa, and other places. I think life is probably going to be ubiquitous, though we still don't have any proof of that yet — and still less, any proof of intelligent life anywhere. But I hope that will be coming in the next decade or so through radio astronomy or, perhaps, the discovery of objects in space which are obviously artificial. Astronomical engineering — that may be the other thing to look for.

"Meeting of the Minds : Buzz Aldrin Visits Arthur C. Clarke" by Andrew Chaikin (27 February 2001) http://web.archive.org/web/20010302082528/http://www.space.com/peopleinterviews/aldrin_clarke_010227.html

Adrienne Willis, Chapter 14, p. 152
2000s, Nights in Rodanthe (2002)

1900s, A Free Man's Worship (1903)

"Koheleth - the Man and his World", p. 3

No. 8.
Maxims and Moral Sentences

The Tragic Sense of Life (1913), VIII : From God to God

Source: Then