Greatest and most famous of all these sacred trees was a quite imaginary one which the Scandinavians called the ash-tree Yggdrasil. Nobody had ever seen it, but everybody among these imaginative people believed in its existence.
It was supposed to be a tree so big that you could not possibly picture it to your fancy, which encompassed the entire universe of sun and moon and stars and earth. And it had three roots, one in heaven, one in hell and one on earth.
The serpent who gnaws the roots of Yggdrasil was of course a heathen idea. Yet you cannot help seeing in him some likeness to the serpent of Genesis who is held to be a symbol of Satan, or the devil. Like Satan he seeks the destruction of the universe. When the roots of Yggdrasil are eaten through the tree will fall over and the end of all things will have arrived.
Luther and the Christmas tree.
Now among the Anglo-Saxons or early inhabitants of England, who were in part descended from the Scandinavians, Yggdrasil survived in the Yule log, which they used to burn on Christmas Eve, as it is still burned in many an English home to-day.
And this is how the pagan tree was transformed into the Christian Yule log:—
The missionaries to the Anglo-Saxons denounced the Yggdrasil superstition. They made their converts hack to pieces all carved figures representing the idolatrous symbol, and then cast the pieces into the flames as a token that the Christ-child had destroyed heathenism.
Among the Germans and the Norsemen, however, the sanctity of the Yggdrasil myth could not be destroyed. It had to be transformed, and transferred to Christian uses by identifying it with some Christian or Jewish symbol like the tree of life in Genesis or the cross of Christ in the New Testament.
Compare the great tree Yggdrasil and its three roots with the description which a certain writer of the early middle ages, called Alcima, gives of the Tree of Life.