Two sorts of cultural historical past had been made in Bethel, N.Y., at 2:00 a.m. on Aug. 16, 1969. The primary was Janis Joplin, barefoot and a bit stewed from partying. She strode onto Woodstock’s plywood stage and confronted the half-million crowd as a solo act, having give up Huge Brother and the Holding Firm a number of months earlier….