"It is not good for human beings to feel secure and experience contentment. Men achieve only by their wants or through their fears." -- Murray Leinster, "The Forgotten Planet" (in Planets of Adventure, 2003, Baen Books, ISBN: 0-7434-7162-8; first published by Gnome Press in 1954).
Bibliographic note from the preface to Planets of
Adventure:The Forgotten Planet was Leinster's
rewrite and novelization of three novellas published previously: "The
Mad Planet" (Argosy, June 1920), "The Red Dust" (Argosy,
April 1921), and "Nightmare Planet" (Science Fiction Plus, June
1953). In the original first two stories, the adventure was set on a
far future Earth. The rewritten novel version was first published by
Gnome Press in 1954.