Sadly, professional photos were prohibited during Bob Dylan’s set.Who: Bob DylanWhen: 9 p.m.Where: MainstageThere are 100 reasons people go to shows–from beer and camaraderie to an excuse to get out of the house–that have nothing to do with music (and there’s nothing wrong with that). But if you’re going out and you’re gonna see a show, you’re probably not in it for the discovery: you want to hear songs you know and love; to hear the songs of memory performed accurately, as they were on record. Toss in a gem of a voice, and it’s a great show.Of the three acts on the mainstage lineup Saturday night–The Decemberists, Neko Case, Bob Dylan–the latter is easily the largest draw in the “he could just play it straight” fan constituency. And yet of the three, his renditions of fan favorites came the furthest away from the originals. And his set was easily the most inspired of the evening. It wasn’t even close.Case in particular was characteristically rote, and at times glib. Was her voice angelic? Of course. But she’s offering few–if any–unforeseen turns in her canon. Last week the National’s Matt Berninger told me that after the band puts a record to rest, they get to know the songs on the road and flesh them out, something that’s apparent in their dynamic live sets. And while there was none of the above-mentioned sense of musical journey and experimentation exhibited by Case and The Decemberists, it’s the cornerstone of Dylan’s set.Sure, it’d be easy to scoff and say, “Yes, but Dylan has ‘Just Like a Woman’ and a host of other hits and crowd pleasers in his artillery.” But it’s not the fact that he plays the hits and classics, it’s how he plays them. He re-imagines them. He does on stage what he could not or did not do with the songs in the studio. For example, it seemed for more than a few moments that “Just Like a Woman” was going to be an instrumental. And the gorgeous arrangement wouldn’t have been a letdown had Dylan not interjected with his gruff howl.Saturday night, in addition to reviving some of the most heavily consumed songs of the last five decades, Dylan, the stoic recluse was downright flirtatious. The man grinned down the audience from the opener, “Rainy Day Women,” straight through to the final encore, an erupting rendition of “Like A Rolling Stone.”Through it all, Dylan crooned, cooed, rotated between guitar and keys, made love to his harmonica, and held the sold-out audience in palm of his hand. Yes, he would have had a rapt audience had he showed up, played bland renditions of songs the entire crowd knew, and walked off the stage. But that’s not good enough for Dylan. He has to be the most engaged person on stage and in the room. Last night he was. But there were more than a few thousand fans in the audience doing everything they could to keep up.