The Celtic Tree of Life symbolizes harmony and balance in the universe. Celts believed that trees were the ancestors of human beings and that the Tree of Life possessed special powers. Trees were a connection to the world of the spirits, doorways into other worlds. The most sacred of all trees is the Oak Tree which represents the center of the world. The Oak tree is the doorway to other worlds, the realm of Fairies and Magic. It was believed that the roots of the tree penetrated the depths of lower worlds, while the branches stretched out to touch the heavens. The tree is a symbol of long life, wisdom and rebirth.