I picked up a box of books from the Harvard Classics set for $5.00 at a yard sale a couple years ago. I finally got around to reading some of them. Volume 2 contains The Golden Sayings of Epictetus, 1st Century Greek Stoic teacher. There is a lot about Stoicism that conflicts with authentic Christianity, but one quote struck me as something very similar to what Paul said around the same time:

Asked, Who is the rich man? Epictetus replied, “He who is content.” (CLXXXII)

In the words of Paul,

But Godliness with contentment is great gain. (1 Timothy 6:6, NIV)