It started with a want ad. Or maybe just with want. The year was 1989, and Jana Cohen Barbe was a young associate at Kirkland & Ellis LLP. Two years removed from the University of Chicago Law School, Barbe was a transactional real estate attorney. She was handsomely compensated. She was on partnership track. She loved her firm. She was burning out. Like a moth seeking a flame, she began reading newspaper want ads with her Sunday morning coffee — “for sport,” as she puts it. “And lo …