In a society which valued oral traditions over the written word, story-tellers or a seanachi and bards played a vital role in linking disparate groups and providing a common identity through shared stories and histories. A bard learned all the different types of poetry and memorized hundreds of songs, poems and legends. They also learned how to play instruments and to read and write although music and poetry was never written down. A bard was the first step taken towards becoming a druid which could take up to twenty years learning by heart the verses and stories. Such sacred knowledge was considered too important to be written down, hence the current lack of information as to the exact role that druids played.
Druid meant “Knowledge of the Oak” which, along with Mistletoe, was considered sacred. Special groves of oak trees provided sanctified, sacrificial area for rites central to the Celtic way of life. What those rites were is impossible to know, given that nothing was ever written down. I imagine druids performed sacrifices and rituals which might actually match the self same rituals we often undergo in our lifetimes – births, deaths, anniversaries, celebration of the seasons and so on. Whether they had a more sinister side as in human sacrifice, I suppose it is possible but certainly not the norm.
Mistletoe was believed to have magical powers and, when growing on an oak tree, must only be cut with a golden sickle.
Druids believed some days were luckier than others and would confer powerful totems of strength, fertility and power, as represented by wild boars, elks and wolves, on warriors.
What medical knowledge current within the Roman Empire would also have been known in Iron Age Ireland. Medical practices such as using maggots to eat wounded and diseased flesh would have been commonplace while boiling willow branches to make a bitter tisane containing some of the pain killing properties of modern day aspirin would be well known. Spider webs and certain types of mosses were packed into and over wounds and apparently acted in some sort of anti-biotic way while valuable and imported Cedar oil was used by the druids to preserve human heads.