She went to the kings who administer law,
Triptolemos and Diokles, driver of horses, mighty
Eumolpos and Keleos, leader of the people, and revealed
the conduct of her rites and taught her Mysteries to all of them,
holy rites that are not to be transgressed, nor pried into,
nor divulged. For a great awe of the gods stops the voice.
Blessed is the mortal on earth who has seen these rites,
but the uninitiate who has no share in them never
has the same lot once dead in the dreary darkness.
(Hymn to Demeter 473-82; trans. Foley)
I would tell you what this means, but "a great awe of the gods stops the voice."