There were three leading groups within the Celtic peoples, and the bards played another special role.
Bards were itinerant singers and poets. They served religion through art. As storytellers, they kept the myths of the people alive.
It is thanks to the bards that we know so much about the Celtic Druids!
As itinerant singers and teachers of the people, they exerted a great formative influence on their hearers. With their visual capacity they could inspire the listening people or, if necessary, encourage them. In times of war they urged the warriors to be brave, but they could also sneer deeply at those who had misbehaved. The bards, then, were trained in praising, and when something did not please them, they would mock and use satire to undermine opponents of their monarch. Thus they were paid by the princes to sing their honors and exploits.
Bards, as the best, were able to arouse courage and enthusiasm, to praise and laud, and to pacify passions. The bards awakened the human conscience. As the Druid shaped the religious ceremonies, so did the Bard with the secular feasts: he gave a mythical background to these gatherings. In this way these singers were the carriers of the culture and they formed the soul of the people.
In Ireland, both in the pre-Christian and early periods of Christianity, there were schools where the bards received their training. This education should not be underestimated, because someone who wanted to become a bard and thus to lead, for example, had to be able to hear music in the deepest silence. Until the tenth century, according to G. Murphy , time signatures[rhythms] and heroic literature were studied, and the apprenticeship could last as long as twelve years. The high art of poetry as practiced by the 'fili', the master poets, aligned them with the Druids and their wisdom. A good bard was said to have eaten the heart of a bird, and that is why his heart had wings and beat them when he sang.
The bard training sharpened the memory and refined the concentration, which thus carried the fili to a level of magical adeptness.
An example of this magical adeptness is the following.
Taliesin, the famous poet, once destroyed the dignity of a society of poets as a child, which demanded a reward from the king. They passed Taliesin who played 'blwrm, blwrm, blwrm' with his fingers over his lips and they ignored the little boy. When they stood before the king, however, all they could do was say 'blwrm, blwrm, blwrm'. The astonished king asked if they were drunk, but the bards had to admit that their behavior was caused by Taliesin!
So there was also another side that the bards had and it was not to be misunderstood. For example, a bard could make magical changes to a landscape or to animals and render both barren. Or he could blister the face of an enemy who dared mock or hurt him.
The pre-Christian Celtic bardic schools survived untouched in Christian times, which is what made Ireland so special. Thus the mythical and heroic songs continued, and these ancient verses were later enriched with Christian texts.
The folk spirit of the Celts was thus strongly associated with the cosmic Christ forces that slowly but steadily became active.
Here is an old Irish poem in which Christ is the shining Logos in the world who illumines the darkness:
In the time before God's Son came,
the earth was a black swamp,
without stars, without sun, without moon,
without body, without heart, without form.
The plains and the hills became light,
the great green sea became light,
the whole earth began to shine,
when God's Son came to earth.
This verse shows that the Celts were a spiritual people; they saw in their own way the gods active in nature, in plants, trees and in the air. Their world was of a spiritual nature. Above all, therefore, they were connoisseurs of word and speech and were acquainted with the power that could emanate from them.
The power of the bards, however, disappeared when the kings could no longer afford their sometimes large companies. They did not want to be mocked for this and were sometimes left in embarrassment (there were times when dozens of bards appeared at court!) Eventually their demands and mockery became too much and this led to them gradually disappearing. Finally, they were protected by the Christian monks and the bards were given a right to exist.
 Jakob Streit, Sonne und Kreuz [Sun and Cross], Freies Geistesleben, Stuttgart 1977
 Caitlín Matthews, The Elements of Celtic Tradition, Element Books, 1989
 G. Murphy, Bards and Filidh, Éigse 2, 1940