she went to the kings who deal justice, Triptolemus and Diocles, the horse-driver, and to doughty Eumolpus and Celeus, leader of the people, she showed the conduct of her rites and taught them all her mysteries, to Triptolemus and Polyxemus and Diocles also — awful mysteries which no one may in any way transgress
The Homeric Hymn to Demeter identifies Triptolemus as the primary mortal recipient of Demeter's mysteries and agricultural rites, establishing his foundational role in the Eleusinian transmission.
, Hesiod, the Homeric Hymns, and Homerica, -700thesis