Socrates woke to the ideal of dispassionate intelligence, Jesus to the ideal of passionate yet self-oblivious worship. Socrates urged intellectual integrity, Jesus integrity of will. Each, of course, though starting with a different emphasis, involved the other.
Unfortunately both these ideals demanded of the human brain a degree of vitality and coherence of which the nervous system of the First Men was never really capable.

Chapter I: Balkan Europe; Section 1, The European War and After (p. 17) - Last and First Men (1930)