Prior to the written word dominating our conscious and intellectual thinking, the Celts combined sound with an oral tradition that was in keeping with their intuitive and (by modern standards) extra sensory and deep perceptive awareness of the oneness of everything. Marion provides a marvellous description of Celtic society and how the beliefs of the Celts often contrasted with those of the Romans.
The Wessex Research Group archive contains those lectures that have been digitised and are freely available as a personal educational tool.
https://www.wessexresearchgroup.org