The author maintains that time does not exist as an entity in itself or as a feature of the universe, such as gravity, light, or strong nuclear force. Nor does it exist as some obscure force or influence which is unknown to us.The fact that what we refer to as time can be applied to all non-living and living matter, and to all events and to all acts performed by living things, dictates the existence of a universal law.This law is the law of unidirectional change (U.D.C.).Our measurement of this change is our measurement of time.