Lucian De saltatione 15

[15] I forbear to say that not a single ancient mysterycult can be found that is without dancing, since they were established, of course, by Orpheus and Musaeus, the best dancers of that time, who included it in their prescriptions as something exceptionally» beautiful to be initiated with rhythm and dancing. To prove that this is so, although it behoves me to observe silence about the rites on account of the uninitiate, nevertheless there is one thing that everybody has heard; namely, that those who let out the mysteries in conversation are commonly said to “dance them out.”

[15] I need hardly observe that among the ancient mysteries not one is to be found that does not include dancing. Orpheus and Musaeus, the best dancers of their time, were the founders of these rites; and their ordinances show the value they attached to rhythm and dance as elements in religion. To illustrate this point would be to make the ceremonial known to the uninitiated: but so much is matter of common knowledge, that persons who divulge the mysteries are popularly spoken of as ‘dancing them out.”