It's the end of the 20th century, in case you haven't been paying attention, and as it comes to a close, so does the first half-century of rock 'n' roll. And just as the general cultural climate feels like a time of simultaneously looking back and looking forward, so do the latest releases from two of the music's towering figures. In a career defined by continual redefinition, it's odd to find David Bowie in a reflective mood, but hours... is steeped in introspection and retrospection, both in tone and form. The Middle Eastern touches of "Brilliant Adventure" sound left over from his years with Brian Eno in Berlin, while the acoustic guitars (when's the last time you heard one of those on a Bowie album?) of "Survive" and "Seven" could come from Hunky Dory. In preparation for hours..., Bowie spent a year listening exclusively to his own music, and the result is a melancholy, approachable album that hits the mark more often than it misses it. After a shaky start ("Thursday's Child" and "Something In The Air" sound like Bowie treading water again), hours... starts to get interesting. This likely has to do with the fact that its best songs ("Survive," "Seven," "What's Really Happening?") are throwbacks to his earlier work, which may or may not have been the intention of Bowie and co-producer Reeves Gabrels (formerly of Bowie's Tin Machine). But there's no arguing with what works, old or new. Just ask Paul McCartney, whose latest album is a throwback to an era that predates even his own relatively early starting point in rock history. Run Devil Run is a collection of a dozen covers from the '50s and early '60s, as well as three originals written in a complementary style. This is McCartney getting back in touch with his roots, just as John Lennon did with 1975's Rock 'n' Roll. In terms of musical innovation, it scores a zero. But in other terms—enjoyability, joyousness of expression, and the way it confirms the enduring power of pure rock 'n' roll—it's off the scale, a momentously enjoyable minor effort that makes a major statement. Joined by unlikely rockabillists David Gilmour (Pink Floyd) and Ian Paice (Deep Purple), McCartney breezes through songs made famous by Fats Domino, Elvis Presley, Big Joe Turner, Chuck Berry, Carl Perkins, and others. As a solo artist, particularly in a decade that's brought oratorios and theme songs to Robin Williams movies, McCartney has rarely sounded so assured, whether singing about riding a mule to the movies on Perkins' "Movie Magg," churning out a blazing cover of Presley's "I Got Stung," or plumbing the depths of loneliness on the obscure skiffle cover "No Other Baby." It also sounds, given what McCartney has been through lately, like a cathartic gesture, a reaffirmation that in this century or the next, the world can be contained in a simple rock 'n' roll song.