Indirect evidence supporting this mirror-birth pattern is strongest in the Christianized form of the Pagan myth. Many writers, from Robert Graves to Stewart Farrar, have repeatedly pointed out that Jesus was identified with the Holly King, while John the Baptist was the Oak King. That is why, 'of all the trees that are in the wood, the Holly tree bears the crown.' If the birth of Jesus, the 'light of the world', is celebrated at mid-winter, Christian folk tradition insists that John the Oak King was born (rather than died) at mid-summer.
It is at this point that I must diverge from the opinion of Robert Graves and other writers who have followed him. Graves believes that at midsummer, the Sun King is slain by his rival, the God of Darkness; just as the God of Darkness is, in turn, slain by the God of Light at midwinter. And yet, in Christian folk tradition (derived from the older Pagan strain), it is births, not deaths, that are associated with the solstices. For the feast of John the Baptist, this is all the more conspicuous, as it breaks the rules regarding all other saints.
So if births are associated with the solstices, when do the symbolic deaths occur? When does Goronwy slay Llew and when does Llew in turn slay Goronwy? When does darkness conquer light or light conquer darkness? Obviously (to me, at least), it must be at the two equinoxes. At the autumnal equinox, the hours of light in the day are eclipsed by the hours of darkness. At the vernal equinox, the process is reversed. Also, the autumnal equinox, called 'Harvest Home', is already associated with sacrifice, principally that of the spirit of grain or vegetation. In this case, the god of light would be identical.
In Welsh mythology in particular, there is a startling vindication of the seasonal placement of the sun god's death, the significance of which occurred to me in a recent dream, and which I haven't seen elsewhere. Llew is the Welsh god of light, and his name means 'lion'. (The lion is often the symbol of a sun god.) He is betrayed by his 'virgin' wife Blodeuwedd, into standing with one foot on the rim of a cauldron and the other on the back of a goat. It is only in this way that Llew can be killed, and Blodeuwedd's lover, Goronwy, Llew's dark self, is hiding nearby with a spear at the ready. But as Llew is struck with it, he is not killed. He is instead transformed into an eagle.
Putting this in the form of a Bardic riddle, it would go something like this: Who can tell in what season the Lion (Llew), betrayed by the Virgin (Blodeuwedd), poised on the Balance, is transformed into an Eagle? My readers who are astrologers are probably already gasping in recognition. The sequence is astrological and in proper order: Leo (lion), Virgo (virgin), Libra (balance), and Scorpio (for which the eagle is a well-known alternative symbol). Also, the remaining icons, cauldron and goat, could arguably symbolize Cancer and Capricorn, representing summer and winter, the signs beginning with the two solstice points. So Llew is balanced between cauldron and goat, between summer and winter, on the balance (Libra) point of the autumnal equinox.
This, of course, is the answer to a related Bardic riddle. Repeatedly, the 'Mabinogion' tells us that Llew must be standing with one foot on the cauldron and one foot on the goat's back in order to be killed. But nowhere does it tell us why. Why is this particular situation the ONLY one in which Llew can be overcome? Because it represents the equinox point. And the equinox is the only time of the entire year when light (Llew) can be overcome by darkness (Goronwy).
It should now come as no surprise that when it is time for Llew to kill Goronwy in his turn, Llew insists that Goronwy stands where he once stood while he (Llew) casts the spear. This is no mere vindictiveness on Llew's part. For, although the 'Mabinogion' does not say so, it should by now be obvious that this is the only time when Goronwy can be overcome. Light can overcome darkness only at the equinox -- this time the vernal equinox.
So Midsummer (to me, at least) is a celebration of the sun god at his zenith, a crowned king on his throne. He is at the height of his strength and still 1/4 of a year away from his ritual death at the hands of his rival. The spear and the cauldron have often been used as symbols for this holiday and it should now be easy to see why. Sun gods are virtually always associated with spears (even Jesus is pierced by one), and the midsummer cauldron of Cancer is a symbol of the Goddess in her fullness. It is an especially beautiful time of the year for an outdoor celebration. May yours be magical!
