Sir James George Frazer (18541941). The Golden Bough. 1922.
the oak crown was sacred to Jupiter and Juno on the Capitol, so we may suppose it was on the Alban Mount, from which the Capitoline worship was derived. Thus the oak-god would have his oak-goddess in the sacred oak grove. So at Dodona the oak-god Zeus was coupled with Dione, whose very name is only a dialectically different form of Juno; and so on the top of Mount Cithaeron, as we have seen, he appears to have been periodically wedded to an oaken image of Hera. It is probable, though it cannot be positively proved, that the sacred marriage of Jupiter and Juno was annually celebrated by all the peoples of the Latin stock in the month which they named after the goddess, the midsummer month of June.
If at any time of the year the Romans celebrated the sacred marriage of Jupiter and Juno, as the Greeks commonly celebrated the corresponding marriage of Zeus and Hera, we may suppose that under the Republic the ceremony was either performed over images of the divine pair or acted by the Flamen Dialis and his wife the Flaminica. For the Flamen Dialis was the priest of Jove; indeed, ancient and modern writers have regarded him, with much probability, as a living image of Jupiter, a human embodiment of the sky-god. In earlier times the Roman king, as representative of Jupiter, would naturally play the part of the heavenly bridegroom at the sacred marriage, while his queen would figure as the heavenly bride, just as in Egypt the king and queen masqueraded in the character of deities, and as at Athens the queen annually wedded the vine-god Dionysus. That the Roman king and queen should act the parts of Jupiter and Juno would seem all the more natural because these deities themselves bore the title of King and Queen.
Whether that was so or not, the legend of Numa and Egeria appears to embody a reminiscence of a time when the priestly king himself played the part of the divine bridegroom; and as we have seen reason to suppose that the Roman kings personated the oak-god, while Egeria is expressly said to have been an oak-nymph, the story of their union in the sacred grove raises a presumption that at Rome in the regal period a ceremony was periodically performed exactly analogous to that which was annually celebrated at Athens down to the time of Aristotle. The marriage of the King of Rome to the oak-goddess, like the wedding of the vine-god to the Queen of Athens, must have been intended to quicken the growth of vegetation by homoeopathic magic. Of the two forms of the rite we can hardly doubt that the Roman was the older, and that long before the northern invaders met with the vine on the shores of the Mediterranean their forefathers had married the tree-god to the tree-goddess in the vast oak forests of Central and Northern Europe. In the England of our day the forests have mostly disappeared, yet still on many a village green and in many a country lane a faded image of the sacred marriage lingers in the rustic pageantry of May Day.