It was the time when panhellenic feeling was probably stronger than ever before or after.
"The Extant Odes of Pindar"
Pindar
On the submission of Eleusis to Athens, the Mysteries became an integral part of the Athenian religion, so that the Eleusinian Mysteries became a panhellenic institution, and later, under the Romans, a universal worship, but the secret rites of initiation were well kept throughout their history.
"The Eleusinian Mysteries and Rites"
Dudley Wright