If the heathen of ancient Europe celebrated, as we have good reason to believe, the season of Midsummer with a great festival of fire, of which the traces have survived in many places down to our own time, it is natural to suppose that they should have observed with similar rites the corresponding season of Midwinter; for Midsummer and Midwinter, or, in more technical language, the summer solstice and the winter solstice, are the two great turning-points in the sun's apparent course through the sky, and from the standpoint of primitive man nothing might seem more appropriate than to kindle fires on earth at the two moments when the fire and heat of the great luminary in heaven begin to wane or to wax. In this way the savage philosopher, to whose meditations on the nature of things we owe many ancient customs and ceremonies, might easily imagine that he helped the labouring sun to relight his dying lamp, or at all events to blow up the flame into a brighter blaze. Certain it is that the winter solstice, which the ancients erroneously assigned to the twenty-fifth of December, was celebrated in antiquity as the Birthday of the Sun, and that festal lights or fires were kindled on this joyful occasion. Our Christmas festival is nothing but a continuation under a Christian name of this old solar festivity; for the ecclesiastical authorities saw fit, about the end of the third or the beginning of the fourth century, arbitrarily to transfer the nativity of Christ from the sixth of January to the twenty-fifth of December, for the purpose of diverting to their Lord the worship which the heathen had hitherto paid on that day to the sun.[631] [The Yule log is the Midwinter counterpart of the Midsummer bonfire.]