It's difficult to believe, but there was a time when Bob Dylan - that bushy-haired, hawk-nosed, nasally voice of a generation - didn't inspire automatic devotion. That time is known, for want of a better phrase, as the 1980s. Dylan stumbled through the decade, finding and losing Jesus, touring with Tom Petty and the Grateful Dead, and recording albums that can only be described as terrible.

How did he come back? How did he restore his iconic image from the 1960s and extend it into a series of critically acclaimed albums?

Dylan's new release, Tell Tale Signs: the Bootleg Series Vol. 8, offers important clues. A collection of unreleased, rare and live recordings from 1989 to 2006, the two-disc set depicts a master musician clawing his way back to artistic relevance.

The comeback dates to 1989's Oh Mercy, which was overseen by U2 producer Daniel Lanois. Several songs from those sessions appear on Tell Tale Signs.

It's clear Dylan sees the album as a turning point, the place he left the middle of the road and started down a craggy path that led to Grammys, Pulitzers and Academy Awards.

But the 1989 songs don't quite know what they want to be. Abstract? Direct? Modern-sounding? Antique? Dylan was writing his way out of a creative impasse, and the process didn't always produce coherent results. "Series of Dreams," for example, was left off the album, and it's easy to see why. For all its ginned-up surrealism, the song's theme and lyrics just can't sustain themselves.

Lanois and Dylan reunited for 1997's Time Out of Mind, and here the real resurgence begins. Dylan abandons attempts to write songs that sound like his classics; he instead pastes together bits of blues standards, cynical aphorisms and Romantic poetry, singing them all in a sepulchral croak.

Tell Tale Signs includes three unreleased songs from those sessions. They're every bit as good as what appeared on the album (it won the Grammy for Album of the Year), and in the case of "Girl from the Red River Shore," even better.

Having found his voice and direction, Dylan ditched Lanois. He didn't need help to get where he was going. His destination was 2001's Love and Theft, perhaps his single best album since the 1960s. Perversely, Tell Tale Signs includes no alternate or unreleased songs from those sessions.

With Love and Theft and its followup, 2006's Modern Times, Dylan completed the trilogy he began in 1997. His songs no longer seem written by a single author. They have instead cohered from numerous sources. Dylan filches lines from Confederate poets, bluesmen and women, Ovid, the Marx Brothers, travel guidebooks, and minstrel routines. He glues it all together with an end-times poetic sensibility and sets the collages to timeworn tunes, played by a spitfire band half his age.

The results aren't for everyone's tastes, especially as Dylan's voice slides from the nasal whine of the late 1980s into the asphyxiated croak of the 2000s. But the late-period soundtrack songs on Tell Tale Signs show him as canny, cranky and funny as ever. "Huck's Tune" even includes the impish line: "All the merry little elves can go hang themselves / My faith is as cold as can be."

The collection tries its best to avoid the chronology outlined above. Songs from different eras jostle against one another, and multiple versions of some tunes confuse matters further. This will probably please most listeners, as Tell Tale Signs avoids the feel of a creaky anthology.

For those who care to look closer, though, this authorized bootleg collection tells the tale of a man learning to create anew. It wasn't easy. To become Bob Dylan again, Bob Dylan had to tear down what came before and start with the building blocks of song and literature that inspired him.

The '80s will do that to a guy.