of an Amesha Spenta into oneself. Each of the seven has an antithetical counterpart, and five of the seven are already assigned one in the Gathas: aša/arta- (truth) is opposed to the druj- (deceit, lies), spəṇta-mainyu to angra-mainyu, vohu-manah is opposed to aka-manah-, xšaθra- to dušae-xšaθra-, and armaiti- to taraemaiti-. Not evident in the Gathas and first appearing in the Younger Avesta are the oppositions of haurvatāt- (wholeness) to taršna- (thirst), and amərətāt- (life) to šud- (hunger). These latter assignments reflect Haurvatat's identification with water and Ameretat's identification with plants. In the Gathas, aša/arta is the most evident of the seven, and also the most commonly associated with wisdom (mazda-). In the 238 verses of these hymns, aša-/arta- appears 157 times. Of the other concepts, only vohumanah- appears nearly as often (136 occurrences). In comparison, the remaining four of the great sextet appear only 121 times altogether: xšaθra-: 56 times; armaiti-: 40; amərətāt-: 14; haurvatāt-: 11 times. In the context of Zoroastrian cosmology, the group of the Amesha Spenta is extended to include Ahura Mazda, represented by (or together with) Spenta Mainyu, who is the instrument or "active principle" of the act of creation.Yasna 44.7, 31.3, and 51.7 It is also through this "Bounteous Force", "Creative Emanation", or "Holy Spirit" that Ahura Mazda is immanent in humankind, and how the Creator interacts with the world. The doctrine also has a physical dimension, in that each of the heptad is linked to one of the seven creations, which in ancient philosophy were the foundation of the universe. A systematic association is only present in later Middle Persian texts, where each of the seven is listed with its "special domain": In the Gathas, Xšaθra [Vairya] does not have an association with a specific creation, and it is only in later texts that this Amesha Spenta is considered the guardian of metals. This anomaly is explained in modern scholarship by the fact that, in Stone Age cosmogony, the sky was considered to be the first of the creations (and thought to be of stone), but metal has no place among the creations (the Bronze and Iron Ages were yet to come). This is also reflected in Zoroaster's revelation, where the sky is "of the hardest stone". Later, with the event of bronze and then iron tools, this sky evolved to being of crystal, which was seen as both of stone and of metal.