I had wondered why I could not find it in Voltair's Zadig! Google identifies it as an old Greek proverb credits Erasmus  quoting it. Even though I read all of H.G. Well's novels as part of a seminar, I don't recall coming across it as his, but I was also taking a course on the Enlightenment at the same time.

"It is not necessary to have hope in order to persevere."