The mosh pit is a moving masterpiece. In the sweat-stained mass, you engage a lineage that extends not just to Bad Brains but to a history of collective motion in riots, protests and crowds — motion that seeks change, devotion, sacrifice, sick stage dives. Step back from the vortex and the scene becomes psychedelic, a surging splatter of limbs and hair. A body falls, the mass makes space. A microphone drops from the vocalist to the audience, the mass moves forward.