the Agathos Daimon is a very primitive fertility-spirit, a conception that long preceded any of the Olympians. He is indeed the inchoate material out of which, as we shall presently see, more than one Olympian is in part made.
Harrison argues that the Agathos Daimon is not a late abstraction but an archaic fertility-daemon, pre-Olympian in origin, whose ritual pouring of new wine gave rise to a personified spirit of beneficence.
, Themis: A Study of the Social Origins of Greek Religion, 1912thesis