It seeks to brings out certain ideas that link together the great diversity of topics that are called "motivational"-or if not all of them, at least adjacent ones, so that readers can move from topic to topic without ever finding themselves on wholly unfamiliar ground. These include such concepts as hierarchical organization (a principle that applies from mating in the stickleback through human schema structure), negative feedback, interaction of external and internal influences on action, and the interplay of excitatory and inhibitory influences.