The principal mysteries were those of Bacchus and Ceres.  The Bacchic mysteries were very generally celebrated throughout Greece, and were a wild nature-worship; partaking of that frenzy which has in all nations been considered a method of gaining a supernatural and inspired state, or else as the result of it.  The Siva worship in India, the Pythoness at Delphi, the Schamaism of the North, the whirling dervishes of the Mohammedans; and some of the scenes at the camp-meetings in the Western States, belong to the same class as the Bacchic orgies.

The Eleusinian mysteries were very different.  These were in honor of Ceres; they were imported from Egypt.  The wanderings of Isis in search of Osiris were changed to those of Ceres or Demeter (the mother-earth = Isis) in search of Persephone.  Both represented in a secondary symbolism the wanderings of the soul, seeking God and truth.  This was the same idea as that of Apuleius in the beautiful story of Psyche.

These mysteries were celebrated at Eleusis by the Athenians every fourth year.  They were said to have been introduced B.C. 1356, and were very sacred.  All persons were required to be initiated.  If they refused it they were supposed to be irreligious.  “Have you been initiated?” was asked in dangerous situations.  The initiated were said to be calm in view of death.  It was the personal religion of the Greeks.

In the greater mysteries at Eleusis the candidates were crowned with myrtle, and admitted by night into a vast temple, where they were purified and instructed, and assisted at certain grand solemnities.  The doctrines taught are unknown, but are supposed to have been the unity of God and the immortality of the soul.  But this is only conjecture.

Bacchus is believed to have been originally an Indian god, naturalized in Greece, and his mysteries to be Indian in their character.  The genial life of nature is the essential character of Bacchus.  One of the names of the Indian Siva is Dionichi, which very nearly resembles the Greek name of Bacchus, Dionysos.  He was taken from the Meros, or thigh of Jupiter.  Now Mount Meru, in India, is the home of the gods; by a common etymological error the Greeks may have thought it the Greek word for thigh, and so translated it.

The Bacchic worship, in its Thracian form, was always distasteful to the best of the Greeks; it was suspected and disliked by the enlightened, proscribed by kings, and rejected by communities.  It was an interpolated system, foreign to the cheerful nature of Greek thought.

As to the value of the mysteries themselves, there was a great difference of opinion among the Greeks.  The people, the orators, and many of the poets praised them; but the philosophers either disapproved them openly, or passed them by in silence.  Socrates says no word in their favor in all his reported conversations.  Plato complains of the immoral influence derived from believing that sin could be expiated by such ceremonies.[262] They seem to have contained, in reality, little direct instruction, but to have taught merely by a dramatic representation and symbolic pictures.