From Julian the Blessed's “Oration to the Mother of the Gods”:
Who then is the mother of the gods? She is indeed the fountain of the intellectual and demiurgic gods who govern the apparent series of things: or certainly a deity producing things, and at the same time subsisting with the mighty Jupiter; a goddess mighty, after one mighty, and conjoined with the mighty demiurgus of the world. She is the mistress of all life, and the cause of all generation, who most easily confers perfection on her productions, and generates and fabricates things without passion, in conjunction with the father of the universe. She is also a virgin, without a mother, the assessor of Jupiter, and the true parent of all the gods: for receiving in herself the causes of all the intelligible supermundane gods, she becomes a fountain to the intellectual gods. The mother of the gods therefore, subsisting after this manner, and who is also called Providence, was inflamed with an impassive love of Attis: for she voluntarily comprehends not only material forms, but much more the causes of these. But, according to the fable, this divine providence, which preserves all generated and perishable natures, fell in love with their demiurgic and prolific cause, and exhorted him to generate rather in an intelligible nature, and to be willing to convert himself to her essence, and to dwell with her divinity; and lastly, she commanded him to associate with no other than herself.
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From Hesiod:
Terrible grief possessed Rhea
When she was going to bear Zeus, father of men and immortals;
Then she implored her own dear parents, star-strewn Heaven and Earth, to
Help her come up with some plan, how she might in secreet give birth to
Her dear son, and how devious Cronus might pay retribution
For what he'd done to his father and for ingesting his children.
Thoroughly they understood and obeyed their favorite daughter.
They foretold to her everything that was fated to happen
Soon to his majesty Cronus as well as his strong-minded son.
They sent Rhea to Lyctos, in the fertile country of Crete.
When she was ready, she gave birth to the last of her children,
Great Zeus, and her Earth-mother took him from Rhea in broad Crete
To nourish the child and as maternal grandmother rear him.
(Daryl Hine edition)
Homeric Hymn to the Mother of the Gods
Sing for me, clear-voiced Muse, daughter of great Zeus, the mother of all Gods and all mortals, who is glad in the sound of rattles and drums, and in the noise of flutes, and in the cry of wolves and fiery-eyed lions, and in the echoing hills, and the woodland haunts; even so hail to thee and to Goddesses all in my song.
(Andrew Lang translation)