[658] Roberts, _Cambrian Popular Antiquities_, 246. CHAPTER XIII. TREE AND PLANT WORSHIP. The Celts had their own cult of trees, but they adopted local cults--Ligurian, Iberian, and others. The _Fagus Deus_ (the divine beech), the _Sex arbor_ or _Sex arbores_ of Pyrenean inscriptions, and an anonymous god represented by a conifer on an altar at Toulouse, probably point to local Ligurian tree cults continued by the Celts into Roman times.[659] Forests were also personified or ruled by a single goddess, like _Dea Arduinna_ of the Ardennes and _Dea Abnoba_ of the Black Forest.[660] But more primitive ideas prevailed, like that which assigned a whole class of tree-divinities to a forest, e.g. the _Fatæ Dervones_, spirits of the oak-woods of Northern Italy.[661] Groups of trees like _Sex arbores_ were venerated, perhaps for their height, isolation, or some other peculiarity. The Celts made their sacred places in dark groves, the trees being hung with offerings or with the heads of victims. Human sacrifices were hung or impaled on trees, e.g. by the warriors of Boudicca.[662] These, like the offerings still placed by the folk on sacred trees, were attached to them because the trees were the abode of spirits or divinities who in many cases had power over vegetation. Pliny said of the Celts: "They esteem nothing more sacred than the mistletoe and the tree on which it grows. But apart from this they choose oak-woods for their sacred groves, and perform no sacred rite without using oak branches."[663] Maximus of Tyre also speaks of the Celtic (? German) image of Zeus as a lofty oak, and an old Irish glossary gives _daur_, "oak," as an early Irish name for "god," and glosses it by _dia_, "god."[664] The sacred need-fire may have been obtained by friction from oak-wood, and it is because of the old sacredness of the oak that a piece of its wood is still used as a talisman in Brittany.[665] Other Aryan folk besides the Celts regarded the oak as the symbol of a high god, of the sun or the sky,[666] but probably this was not its earliest significance. Oak forests were once more extensive over Europe than they are now, and the old tradition that men once lived on acorns has been shown to be well-founded by the witness of archæological finds, e.g. in Northern Italy.[667] A people living in an oak region and subsisting in part on acorns might easily take the oak as a representative of the spirit of vegetation or growth. It was long-lived, its foliage was a protection, it supplied food, its wood was used as fuel, and it was thus clearly the friend of man. For these reasons, and because it was the most abiding and living thing men knew, it became the embodiment of the spirits of life and growth. Folk-lore survivals show that the spirit of vegetation in the shape of his representative was annually slain while yet in full vigour, that his life might benefit all things and be passed on undiminished to his