Source: ‘Part II: After the Bronze Age,’ Chariot of the Sun and Other Rites and Symbols of the Northern Bronze Age, 1969, pp. 159-161.
Sacred groves are known to have been important in the cults of the Germanic and Celtic peoples, and there is evidence that the tree was an important symbol in the Celtic world (Ross, pp. 33-8). The Celtic deity identified with Mercury seems to have been especially connected with trees in Gaul, while the warriors on the Gundestrup bowl are seen to bear a tree above their spears. Early cremation urns of the Germanic peoples occasionally bear the representation of a tree (Lechler, pp. 355-6), and one is clearly depicted on one of the finest of the early carved stones of Gotland, believed to be of fifth-century date, found at Sanda (Lindqvist, 1962, p. 7), set between the disks and the head of a monster. The significance of tree symbolism is difficult to establish clearly in memorials of the later period, because of confusion with the symbol of the Christian cross.
It must be noted, however, that the conception of the World Tree was one of the most powerful and effective religious symbols of the North in pre-Christian times, and one which has left a deep impression on the literature, particularly on the Edda poems. The tree Yggdrasil was represented as the centre of the worlds of gods, men and giants, and was closely linked with the conception of the pagan gods, particularly Odin and Heimdall. It was on this tree that Odin hung in his pursuit of wisdom, and Anne Ross (p. 34) points out that there are signs of a similar conception in the story of Lieu taking refuge in an oak after he has been wounded by a spear, found in the Welsh Mabinogion. A tree with an eagle at the top and a serpent at the root, as Yggdrasil is described in the Edda poems, forms a link between earth and heaven, and this is a very ancient symbol, found far outside Scandinavia, in the Mediterranean area, the Near East, and among the Finno-Ugric peoples. The idea of the central pillar of the world, Irminsul, was known among the Germanic peoples at least as early as the ninth century (de Vries, 1952, p. 18), and it has been thought that Irmin was one of the names of the early sky god. If this is so, it is not surprising to find traces of a tree symbol in the Bronze Age in association with the sun-disk.
In Germany and Scandinavia, it was customary for the family tree to stand near the house, and occasionally the house itself seems to have been built around it (Davidson, 1960, pp. 4-5); the luck of the family depended on the preservation of this tree. One aspect of such a conception in Viking times is that of the ‘high seat pillars’, the name given to the wooden columns forming the main support of the building, and of ceremonial importance in the Scandinavian hall, since the most important seats were set between them. They were connected with the cult of Thor, and his worshippers are said to have taken such pillars with them from his temples in Norway in order to use them in Iceland, when they set up new dwellings for their god. In Germany there was a close link in pagan times between the god of thunder and the oak tree, and early shrines of the god seem to have been set in oak forests. Similarly the oak was one of the sacred trees of the Celts (Ross, p. 34), and others were the yew and the ash, both of which were remembered in Scandinavian tradition(Davidson, 1964, p. 191). Later in the Viking Age we hear of sacrificial victims of the gods being hung from trees in the sacred grove at Old Uppsala, and this seems to be a continuation of a custom recorded among the heathen Germans by Greek and Latin writers. Thus there is a link with the cult of the god of battle, Wodan/Odin, as well as with the thunder-god.
One particular form of the tree symbol as found in the art of the tenth century is that of a tree with two birds beside it or on its branches (Fig. 77). This is found on stones of Scandinavia and Viking Britain (Davidson, 1950), and is linked with a scene where a man kills a dragon, thought to be an early form of the story of Sigurd the Volsung. In the later literary versions of this tale, Sigurd is warned by the two birds of the treachery of the smith Regin, the dragon’s brother, after the touch of dragon’s blood on his tongue has given him understanding of the birds’ speech. The fact that the symbol of two birds on the tree is found much farther afield, in many parts of Asia, and in Iran and Mesopotamia in very early times (Werner, pp. 69 ff.), shows it to have been a powerful one in pre-Christian times, and it is significant to find it in the northern Bronze Age in Scandinavia.