Hello William, and thank you for opening this line of discussion. I know it is one that I am interested in.

One thing that occured to me tonight, after days of reading this thread, as well as Dr. Fagan's post is that this is something that Caesar only heard about. We can infer that Caesar would have heard about the role of Druids from his friend, and fellow holyman, Diviciacus, the Aedui Druid. One can only assume that he was Caesar's main source on Celtic Religion, since he mentions no other Druid by name. Now the one thing we have to ask ourselves about Diviciacus the Aeduean Druid is How much do we know about him?

We know that he was a guest in Rome, and that Romans thought Druids were a myth. Cicero knew him though.

Nor is the practice of divination disregarded even among the uncivilized, if indeed there are Druids in Gaul - and there are, for I knew one of them myself, Divitiacus, the Aeduan, your guest and eulogist.
He claimed to have that knowledge of nature which the Greeks call "physiologia", and he used to make predictions, sometimes by means of augury and sometimes by means of conjecture.

Cicero, De Divinatione, I, xli, 90.

So we know that he was in Rome and we can assume that he was in Rome in asking for aid against the Helvetti, the reason Caesar went into Gaul in the first place. We can also assume that Diviciacus was also villifying his enemies as well, and this act was reported to Caesar by the Druid, and Caesar only included it in his Commentaries to justify his presence in Gaul. So from Caesar we are still at a loss about the Wickerman. Lets take a look at Archaeological evidence.

There is no archaeological evidence, but we do know that the Celts practiced human sacrifice from evidence at Maiden Castle in Britain and Triers in Germany (ancient Belgica). If there was a wickerman, what kind of evidence would we find? Well, most of the body would be burned to ashes, but there would still be bone fragments, ash, and other parts of the structure that wasn't burned completely.

This is purely speculative on my part, but I have been researching alot of Celtic villages and I notice that they all are on a river. The river is a source of not only food from fish, but freshwater. Water to wet the crops, make the beer, and drink (although if they are downstream from another village, they would find out quick about fecal diseases and boil the water).

But water is also used to wash away the mess. The Celts may have set up their ritual statue in a flood plain, where the evidence would be washed away. This ritual may not have sit well with some Celts, either, and the Druid Diviciacus may have elaborated, or resorted to the Roman trick of Barbarizing his opponent, and why not? Caesar certainly appreciated it.

I keep thinking of the scene from MacBeth where the Lady Macbeth can't wash the blood off her hands. It seems that all the Celts have to pay for the offenses of the few, and all are villified.