Julian Cope presents Head Heritage

Beltane and Samhain definately predate the celts, they were the feast of the Nine Maidens and Three Fates etc... all over Europe and were calcualted astrologically on conjunctions of the Moon, Venus, Pleiades and sunset and sunrise. Samhain, in particular, was the time of year when the dead are judged for their lives and the living judged for the coming year by the Weird Sisters, and as such the veil between the worlds is thin and all sorts of things happen. Beltane was the opposite, where nothing you did would be judged and you could go a bit mad.

There's some doubt as to whether these were just the four main ones which had law court sessions attached to them too, and the other festivals weren't mentioned by early christian chroniclers as being vulgar pagan folk festivals.

I like Ellis-Davidson, got a few titles mostly relating to northern tradtions though. MacNeill, Máire: The Festival of Lughnasa (Oxford University Press) 1962. Republished 2008. ISBN 0-906426-10-3. It's the book all the other books used to quote, but was very rare to find a copy. It's 900 pages, but I heard the new print might be in two books and somewhat abbreviated.