Among the sacred trees in many legends, the mighty oak stands noble and tall. Many people consider the Oak as “The Tree of Life”. The oak tree in lore and myth represents great symbolic meanings to the pantheons of mythology, to the druids, the faeries, and many cultures around the world. This truth has been told since before the times of Merlin.
The ancient Celtic peoples held the Oak tree in great honor for its endurance and expansive growth. They considered the Oak tree to have attributes of life, family, strength, wisdom, nobility, longevity, heritage, and honor. Since the Oak attracts lightning, the Celts considered it to have powerful energies and associated it with Dagda, one of their most important gods.
Other gods that the Oak is attributed to in ancient beliefs are Jupiter, Thor, Zeus, Herne, Janus, Rhea, Cybele, Hecate, Pan, Dianus, and Erato.
Some Native American tribes, as well as many other cultures, held the Oak in high esteem due to its strength, size, longevity, and the acorn which is a very good source of nutrition. The acorn is also seen as a symbol of life -- for from the acorn, a mighty Oak grows.
Within the sacred circle of stones in an oak grove, the Druids conducted their secret rituals. The mistletoe that grew high in the oak was sent from Heaven by the god who chose the tree as sacred. They were priests of the god. They cut the mistletoe with the golden sickle during the ceremony. Anything that grew on the sacred tree was especially revered.
In the 1st century AD, Pliny the Elder wrote of a religious ceremony involving the Oak and Mistletoe that was held in Gaul by druids who wore white robes. He referred to them as magicians and that the oak and mistletoe are very sacred to them. Druids, he continued, when gathering the mistletoe do so with "great ceremony" then send hails to the moon. Hailing, he said, means "healing all things". It is a priest in white robes that collects the mistletoe from high up in the oak. With a golden sickle the priest cuts down the mistletoe which must be caught in a white robe. After the mistletoe is properly gathered, the druids partake in a feast below the oak tree.
The Oak Grove was their major meeting place, where they held their rituals, for it provided protection and power for their magick and spells.
In Anglesea on Mona's Isle in Wales there stands the "Holy Groves" of the Druids. It is an ancient sacred site. In AD 60 the Roman general Gaius Suetonius Paulinus, determined to break the power of the Celtic druids, attacked the island, destroying the shrine and the sacred groves -- remnants of the sacred oaks can still be found there.
The oak represented doorways to other realms. It was believed to provide protection and shelter when passing through to and from other realms. This noble tree was considered the giver of great powers and was most exalted of all trees by the Druids. An oak grove was their most spiritual place.
It was the custom and practice of the Druids to meet in mighty Oak groves and beneath old Oak trees -- they preferred that their meetings and ritualistic ceremonies be conducted outside where they had stronger connection to nature and the faeries, like the tree Dryads.