Hermes presided over the rustic art of divination by pebbles, practised in the highlands of shepherds and cattle-herders.
He was said to have learnt the art from certain Nymphai known as Thriai, given to him by Apollon in a trade for the music of the pipe.
Homeric Hymn 4 to Hermes 550 ff (trans. Evelyn-White) (Greek epic C7th to 4th B.C.) :
“[Apollon to Hermes:] ‘As for sooth-saying, noble, heaven-born child, of which you ask, it is not lawful for you to learn it, nor for any other of the deathless gods . . . But I will tell you another thing, all-glorious (erikydes) Son of Maia and Zeus who holds the aegis, luck-bringing genius of the gods (daimon eriounes theon). There are certain holy ones, sisters born – three virgins gifted with wings: their heads are besprinkled with white meal, and they dwell under a ridge of Parnassos. These are teachers of divination apart from me [i.e. of divination by pebbles], the art which I practised while yet a boy following herds, though my father paid no heed to it. From their home they fly now here, now there, feeding on honey-comb and bringing all things to pass. And when they are inspired through eating yellow honey, they are willing to speak truth; but if they be deprived of the gods’ sweet food, then they speak falsely, as they swarm in and out together. These, then, I give you; enquire of them strictly and delight your heart: and if you should teach any mortal so to do, often will he hear your response – if he have good fortune. Take these, Son of Maia [and preside over this primitive form of divination].’”