The Celtic tree of life is a symbol that represents the interconnectedness of life on Earth and a link between the human world and the world of the spirits. It is usually depicted as a single tree with branches spreading wide at the top and roots spread out at the bottom.
Although Celtic versions of the tree of life are popular, the symbol was used around the world. Some religions gave it slightly different meanings, but many are similar to the Celtic interpretation. The design also varies somewhat. The Celtic version dates to at least 2000 B.C., based on carvings found in Northern England.
Trees played a significant role in ancient Celtic life and beliefs. The Celts saw certain trees as sacred and used them as part of various religious ceremonies. They would leave offerings at the base or tied to the leaves of some of these sacred trees. Ogham, the ancient Celtic alphabet, was also based on trees. Each letter represented a type, such as oak.
The link between trees and the spirit world may be because ancient people observed the tree seemingly complete an entire life cycle each year. In the spring, new buds and leaves would form, then grow and stay green throughout the summer. In the fall, the leaves begin to die, and in the winter, the entire tree appears dead. Ancient Celts used this to symbolize death and rebirth.