But at least there's a band out there that's willing to draw those lines and proceed alone if no one steps forward to follow them. After all, in above-ground hip-hop these days, what passes for experimentation is Jay-Z stringing about four worthwhile songs over two separate discs, as he does on The Blueprint 2: The Gift & The Curse. (The skills Jay-Z showed on last year's The Blueprint and Unplugged discs now look like an aberration instead of an absolute fact, in light of the complete lack of same on this year's R. Kelly team-up Best of Both Worlds and The Blueprint 2.) And "Water" isn't The Roots' only challenge to their listeners; there are a few other "are you in or are you out?" moments on Phrenology, such as the half-minute, full-speed "!!!!!!!" (a nod to Bad Brains and Minor Threat, of all things) and the rock-and-soul cover of Cody Chesnutt's "The Seed (2.0)," which features iconoclast Chesnutt on vocals and guitar. The rest of Phrenology, however, acts as a live-band companion piece to Missy Elliott's Under Construction (see Todd Levin's take on that below), celebrating the old school while enrolling in the new one. Cross that line. It'll be OK. I promise.