Most intriguing was Engelmann's concept central to almost all his hypotheses. Both the intensity and complexity of an average individual's behavior cannot increase simultaneously. As one goes up the other goes down. Twenty-three centuries after Aristotle we find an explanation for his assertion, "If we take intense delight in one thing, we cannot do anything else at all." We also find that behavioral intensity increases with rising interaction frequency even as complexity declines. Therein lies the source of both power exercise and the widespread approval of it in modern times.