were supposed to inspire with prophecy, and to breathe of the god.
The gloom of caverns, naturally the brooding-place of awe, was deemed
a fitting scene for diviner revelations--it inspired unearthly
contemplation and mystic revery. Zoroaster is supposed by Porphyry
(well versed in all Pagan lore, though frequently misunderstanding its
proper character) to have first inculcated the worship of caverns
[37]; and there the early priests held a temple, and primeval
philosophy its retreat [38]. Groves, especially those in high places,
or in the neighbourhood of exhaling streams, were also appropriate to
worship, and conducive to the dreams of an excited and credulous
imagination; and Pekah, the son of Remaliah, burnt incense, not only
on the hills, but "under every green tree." [39]

These places, then--the mountain, the forest, the stream, and the
cavern, were equally objects of sanctity and awe among the ancient
nations.

But we need not necessarily suppose that a superstition so universal
was borrowed, and not conceived, by the early Greeks. The same causes
which had made them worship the earth and the sea, extended their
faith to the rivers and the mountains, which in a spirit of natural
and simple poetry they called "the children" of those elementary
deities. The very soil of Greece, broken up and diversified by so
many inequalities, stamped with volcanic features, profuse in streams
and mephitic fountains, contributed to render the feeling of local
divinity prevalent and intense. Each petty canton had its own Nile,
whose influence upon fertility and culture was sufficient to become
worthy to propitiate, and therefore to personify. Had Greece been
united under one monarchy, and characterized by one common monotony of
soil, a single river, a single mountain, alone might have been deemed