The Druids, the high priests of the Celts, would spend twenty years learning the traditions and oral lessons. The native lore of Wales and Ireland, the oldest outside of classical sources, is a great repository of pre-Christian myth and practices. Fragmentary texts transcribed during the fourteenth and fifteenth centuries provide us with ancient legends and heroic tales, influenced by the times of the scribes. Archaeological evidence provides us with more clues. The Celts of Ireland maintained their cultural integrity until close to 500 AD, and it is there where the pagan Celtic mythology has been best preserved.
Animal symbolism found in Celtic myths include boars, birds, serpents, fish, horse and cattle.
Boars symbolise courage and strong warriors. Power and strength is attached to the bristles of the boar, which was held in high esteem by the Celts. There are many examples of supernatural boars and their adventures in the literary traditions of the Irish and the Welsh. The otherworld feast is supposed to be sustained by magical pigs which, no matter how many times they are cooked and eaten, are alive again the next day to be cooked again. Fish, especially salmon are associated with knowledge and secrets.