... The ancient Iranian theology taught that two antagonistic personalities, Ahura-Mazda and Angro-Mainyus, ruled existence, and, from eternity to eternity were engaged in a perpetual contest, each seeking to injure and destroy the other.  They are described as real persons, possessing will, intelligence, power and consciousness.  According to the learned, Ahura means living, and is used for "living being."  Some would translate it by spirit, only that we must not regard absolute immateriality as implied in it.  Maz is an intensitive and means "much."  Da, or dao, may mean either giving or knowing.  "Ahura-Mazda" would thus mean "the much knowing spirit" or "the much giving spirit." (Intelligence, v.6, Jun-Nov, 1897)