Zosimus (1. v. [c. 41] p. 355, 356) speaks of these ceremonies like a Greek unacquainted with the national superstition of Rome and Tuscany. I suspect that they consisted of two parts, the secret and the public; the former were probably an imitation of the arts and spells by which Numa had drawn down Jupiter and his thunder on Mount Aventine.
__Quid agant laqueis, quae carmina dicant,
Quaque trahant superis sedibus arte Jovem,
Scire nefas homini.
The ancilia or shields of Mars, the pignora Imperii, which were carried in solemn procession on the calends of March, derived their origin from this mysterious event (Ovid. Fast. iii. 259-398). It was probably designed to revive this ancient festival, which had been suppressed by Theodosius. In that case we recover a chronological date (March the 1st, A . D . 409) which has not hitherto been observed .