“It is a time-honored role for artist as designator, to point at the stuff of the physical world and revision it as art, harkening back to the readymade. But Gates’s decision to ‘bump off from art’ and live ‘in the sphere of dirt, the dirty, the stuff that we think is in the ground’ was revelatory, leading to invitations to Davos and a TED Talk, where he talked about how he revived a neighborhood with imagination and hard graft.”