In one of Robert Graves’ Claudius novels (Claudius The God?) Claudius relates the trials of aspiring druidical bards, who apparently had to perform various ridiculous Ninja-style feats of awesomeness if they were to qualify for the position.
If I remember correctly, one trial required the applicant to be submerged, naked, in an enclosed casket of ice water, with no light and only a straw to breath through, for 24-48 hours, during which the applicant was expected to compose some epic poem (both music and verse), and to immediately and flawlessly perform that poem upon being hauled out of his casket.
Is my memory of the text correct? And if so, did Graves pull this story out of thin air, or does it have some basis in fact (or at least legend)? Were the Druids European Ninjas?
Thin air. We know they did go through intensive training in which they had to both memorize and compose poems, but we just don’t have that level of detail. Even the “both music and verse” part is unclear. We assume that they were trained in music, but there is no solid evidence from ancient sources.
I have to say, though, having read a lot of medieval Irish literature (there is no surviving Gaulish literature), they probably would have liked this idea.
Although there are several inaccuracies in the Claudius novels, Graves wasn’t the type to pull details like that out of “thin air”. I’ll almost guarantee you that there is an ancient text out there that purports that such rituals actually took place. That doesn’t mean it’s true, just that the story emerged from thin air long before Graves came along.
That is a guarantee you will lose. You will find a reference to a 20-year education cycle in ancient sources, and you will find more detail in medieval Irish sources about the education of bards, which probably continue the druidic tradition but are not exactly the same thing. The darkness and the nudity (or at any rate partial undress) are one thing, but I am afraid you’ll have to give Graves some credit as a creative author for the water barrel idea.
There is no doubt that Graves read Iolo Morganwg (I didn’t realize you were counting antiquarian writings as “ancient text”), but I don’t think this incident is from Morganwg. Not his style. I haven’t read his entire corpus, though, so I could be wrong here.
I’m just saying, as inaccurate as he was at times, Graves considered himself an historian as much as a novelist. He would find find details (like those in the OP) in historical texts and shoehorn them into his story.
From what I remember, the details of the bard hazing play no role in the novel other than historical interest. It doesn’t advance the story or help develope any of the main characters. Why would he go to the trouble of creating such a ritual from whole cloth when there were, no doubt, many similarly interesting stories that he could pull out of his research?