Canopied live oak forest
Large and impressively long-lived, the oak was one of the most important TREES to the Celts. In part, this was because of the oak’s usefulness: It provides abundant acorns, which were in ancient times a favored food of PIGS, whose flesh then became part of the human diet; its long-lasting wood is sought after for building; its bark produces a substance useful for tanning leather. The oak’s usefulness extended to the spiritual plane as well; according to Roman author Pliny the Elder, the Celts harvested MISTLETOE from oak trees for ritual use in curing disease and encouraging human FERTILITY.
Oak forests were common in continental Gaul, where we find early evidence of their sanctity: Construction of oak funeral houses by HALLSTATT and LA TÈNE peoples suggests that the tree was connected with the afterlife or OTHERWORLD. The oak may have been associated with a specific god, although which one is not clear, because documents date only to Roman times, when Maximum Tyrius claimed the oak symbolized the father of gods, who lived within the tree; the so-called Jupiter columns (JUPITER being the Roman version of Zeus) found in Gaulish temples have been interpreted as indoor substitutes for great trees dedicated to the god.
Although trees in general were sacred to the Celts, who practiced their rituals in NEMETONS or sacred groves, the Celtic priesthood of DRUIDS held the oak to be the most sacred tree; indeed, the very word druid is connected to an ancient word for “oak.” The Roman poet Lucan described the druids as using acorns in their prophetic rituals, masticating them until they saw visions; the story is hard to credit, because no hallucinatory substances have been isolated in acorns. Wooden images from the pre-Roman and Roman periods have been found, carved of the strong and lasting wood of the oak.
Belief in the sanctity of the oak survived into the post-Celtic era, when folklore envisioned the oak as a living being that, when cut, cried out or took revenge upon the forester, maiming or killing him as it fell. An oak was believed to make a desperate racket when felled, loud enough to be heard a mile away. FAIRY folk were thought to live in or around oaks; together with the ASH and the THORN, the oak constituted the sacred tree trinity that marked fairy places.
The centrality of the oak in ancient Celtic life can still be detected in names that embody the tree: the Celtic capital of the Galacians in Turkey, Drunemeton (“sacred oak grove”); and the Irish abbey towns of KILDARE (“church of the oak”) and of Durrow (“plain of oaks”).
Sources: Green, Miranda. Symbol and Image in Celtic Religious Art. London: Routledge, 1989, p. 152; Ross, Anne. Pagan Celtic Britain: Studies in Iconography and Tradition. London: Routledge & Kegan Paul, 1967, p. 33.
British folkloric figures. Occasionally in the north of England, references are found in oral literature to FAIRY people who lived in great OAKS; an old rhyme holds that “fairy folks/are in old oaks.” Especially powerful were oaks that regenerated themselves after being cut; the saplings that came forth in such circumstances were regarded with awe. In the Cotswolds each village had a sacred tree, usually an oak, where fairy beings were believed to hide. The artist Beatrix Potter used the tradition in her book The Fairy Caravan, in which oak people wore toadstools for caps.
Source: Briggs, Katharine M. The Folklore of the Cotswolds. London: B. T. Batsford Ltd., 1974, p. 121.