He was especially worshipped on hill-tops (like the Aztec rain-god); for example, on Ithome, Parnes, Cithgeron, and the Lycaean hill of Arcadia. On the Arcadian mountain, a centre of the strangest and oldest rites, the priest of Zeus acted as what the African races call a "rainmaker". There was on the hill the sacred well of the nymph Hagno, one of the nurses of the child Zeus. In time of drought the priest of Zeus offered sacrifice and prayer to the water according to ritual law, and it would be interesting to know what it was that he sacrificed. He then gently stirred the well with a bough from the oak, the holy tree of the god, and when the water was stirred, a cloud arose like mist, which attracted other clouds and caused rain. As the priest on a mountain practically occupied a meteorological observatory, he probably did not perform these rites till he knew that a "depression" might be expected from one quarter or another.* * See similar examples of popular magic in Gervase of Tilbury, Otia Imperiidia; Liebrecht, ii. 146. The citation is due to Freller, i. 102. Wonderful feats of rain-prophecy are done by Australian seers, according to Mrs. Langloh Parker and others. As soon as we meet Zeus in Homer, we find that he is looked on, not as the sky, but as the deity who "dwells in the heights of air," and who exercises supreme sway over all things, including storm and wind and cloud. He casts the lightning forth (--------) he thunders on high (--------), he has dark clouds for his covering (--------) all these imposing aspects he is _religiously_ regarded by people who approach him in prayer. These aspects would be readily explained by the theory that Zeus, after having been the personal sky, came to be thought a powerful being who dwelt in the sky, if we did not find such beings worshipped where the sky is not yet adored, as in Australia. Much the same occurred if, as M. Maspero points out, in Egypt the animals were worshipped first, and then later the gods supposed to be present in the animals. So the sky, a personal sky, was first adored, later a god dwelling in the sky. But it is less easy to show how this important change in opinion took place, if it really occurred. A philological theory of the causes which produced the change is set forth by Mr. Keary in his book _Primitive Belief_. In his opinion the sky was first worshipped as a vast non-personal phenomenon, "the bright thing"(_Dyaus_). But, to adopt the language of Mr. Max Müller, who appears to hold the same views, "Dyaus ceased to be an expressive predicate; it became a traditional name";* it "lost its radical meaning". Thus where a man had originally said, "It thunders," or rather "He thunders," he came to say, "Dyaus" (that is, the sky) "thunders". * Select Essays, ii. 419.