Survival of self, of species, and of environment, these are what drive humans. You can observe how the order of importance changes in a lifetime. What are the things of immediate concern at a given age? Weather? The state of the digestion? Does she (or he) really care? All of those various hungers that flesh can sense and hope to satisfy. What else could possibly matter?
Attributed to: Leto Atreides II
From Chapter 35 of Heretics of Dune by Herbert, Frank