The Celts, incidentally, pretty much invented Halloween. Back in the day, it was called Samhain, celebrating the end of summer with a ceremonial igniting of fires as a symbol of the winter ahead and spring on the other side of it. Also, the boundary between the worlds of life and death were thin. Which they might be again at the 12th Annual Highland Games & Celtic Festival because of the abundance of men throwing around telephone poles, hammers and axes. The history of the Celts includes tons of music too, re-created over the weekend by such outfits as D.C.’s Scythian, Scotland’s Albannach, our own Uisce Beatha and others. Oh, and how could a weekend be complete without a rousing show of “ferret legging,” that original trick-or-treat for the pants. The festival runs Saturday and Sunday, Oct. 28-29, starting at 9 a.m. at the Richmond Raceway Complex. Tickets are $18-$26. Call 569-3200 or visit www.statefairva.org. S