The argument is presented that motivation is equated to energy mobilization, and that the mechanism involved in all such instances of arousal is a discrepancy-detecting and -reducing mechanism. Motives are specific categories of discrepancy but they operate through a common arousal system. This system, further, may be coopted into (integrated into) processes involving social comparison, relative deprivation, discrepancies with respect to ego-involved persons and objects, and industrial, social, and political motives. While biological homeostasis provides the basic CNS system, other forms of discrepancy-triggered energy arousal must be recognized as important. Hedonism and theories of curiosity, as well as other similar factors, can be subsumed under discrepancy theory.