They came from the East, the West, the North and the South Side, pilgrims all: the stoned and the rehabbed, wistful greybeards and start-up dreamers, CEOs and short-sellers. Last night was the first show of the group’s three-night Fare Thee Well run, billed as the last shows the surviving Grateful Dead members will play as a group. It was beautifully executed under a waning gibbous moon, on a cool summer evening, with a soft breeze coming in off Lake Michigan. About 70,000 people danced and sang through the night, packing one-hitters, drinking, hugging and welling up. The night was a perfectly unpredictable mix of classics and curveballs, opening with “Box of Rain,” the American Beauty gem written by Phil Lesh for his dying father, it was the last song the band played together when Garcia was alive, performed on the same spot in Chicago nearly 20 years ago.