The quote is from Herodotus Book 9 Chapter 122, "Soft lands breed soft men", by Cyrus the Persian.
Reference: http://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:19...
Reference: http://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:19...
This all is reminding me of another saying, a spartan one. A Spartan woman was asked why they do not submit to their men, and she replied with "strong men are not born from weak women".
If anyone is liking these forms of phrases (short, insightful), there is a word just for it: Laconic [1].