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.
Eleusis was one of the twelve originally independent cities of Attica, which Theseus is said to have united into a simple state. Leusina now occupies the site, and has thus preserved the name of the ancient city.
Theseus is portrayed by Virgil as suffering eternal punishment in Hades, but Proclus writes concerning him as follows: "Theseus, and Pirithous are fabled to have ravished Helen, and to have descended to the infernal regions—i.e. they were lovers of intelligible and visible beauty. Afterwards Theseus was liberated by Pericles from Hades, but Pirithous remained there because he could not sustain the arduous attitude of divine contemplation."
Dr. Warburton, in his Divine Legation of Moses, gives it as his opinion that Theseus was a living character who once forced his way into the Eleusinian Mysteries, for which crime he was imprisoned on earth and afterwards damned in the infernal regions.
The Eleusinian Mysteries seem to have constituted the most vital portion of the Attic religion, and always to have retained something of awe and solemnity. They were not known outside Attica until the time of the Median wars, when they spread to the Greek colonies in Asia as part of the constitution of the daughter states, where the cult seems to have exercised a considerable influence both on the populace and on the philosophers. Outside Eleusis the Mysteries were not celebrated so frequently nor on so magnificent a scale. At Celeas, where they were celebrated every fourth year, a hierophant, who was not bound by the law of celibacy, as at Eleusis, was elected by the people for each celebration. Pausanias is the authority for a statement by the Phliasians that they imitated the Eleusinian Mysteries. They maintained, however, that their rendering was instituted by Dysaules, brother of Celeus, who went to their country after he had been expelled from Eleusis by Ion, the son of Xuthus, at the time when Ion was chosen commander-in-chief of the Athenians in the war against Eleusis. Pausanias disputed that any Eleusinian was defeated in battle and forced into exile, maintaining that peace was concluded between the Athenians and the Eleusinians before the war was fought out, even Eumolpus himself being permitted to remain in Eleusis. Pausanias, also, while admitting that Dysaules might have gone to Phlias for some cause other than that admitted by the Phliasians, questioned whether Dysaules was related to Celeus, or, indeed, to any illustrious Eleusinian family. The name of Dysaules does not occur in the Homeric Hymn to Demeter, where are enumerated all who were taught the ritual of the Mysteries by the goddess, though that of Celeus is mentioned:—
She showed to Triptolemus and Diocles, smiter of horses
And mighty Eumolpus and Celeus, leader of people,
The way of performing the sacred rites and explained
to all of them the orgies.
Nevertheless, according to the Phliasians, it was Dysaules who instituted the Mysteries among them.
The Pheneatians also had a sanctuary dedicated to Demeter, which they called Eleusinian, and in which they celebrated the Mysteries in honour of the goddess. They had a legend that Demeter went thither in her wanderings, and that, out of gratitude to the Pheneatians for the hospitality they showed her, she gave them all the different kinds of pulse, except beans. Two Pheneatians—Trisaules and Damithales—built a temple to Demeter Thesuria, the goddess of laws, under Mount Cyllene, where were instituted the Mysteries in her honour which were celebrated until a late period, and which were said to be introduced there by Naus, a grandson of Eumolpus.
"Much that is excellent and divine," wrote Cicero, "does Athens seem to me to have produced and added to our life, but nothing better than those Mysteries by which we are formed and moulded from a rude and savage state of humanity; and, indeed, in the Mysteries we perceive the real principles of life, and learn not only to live happily, but to die with a fairer hope." Every manner of writer—religious poet, worldly poet, sceptical philosopher, orator—all are of one mind about this, that the Mysteries were far and away the greatest of all the religious festivals of Greece.