Bob Dylan by Milton Glaser. The iconic, mandatory wall poster in every ’60s/’70s bedroom and dorm room. Initially issued inside the first pressings of Bob Dylan’s Greatest Hits double LP and sold separately thereafter. It has since become one of the most famous rock images.

Has it really been only seventy-five years, or several lifetimes? Happy Birthday this week to Robert Zimmerman, the kid from Duluth, Minnesota who became Bob Dylan, the Artist from Everywhere. We’ve known him since forever, it seems, and yet we don’t and probably never have known him, not really.

What we do know is the precociously profound and prolific songwriter who, for more than half a century now, has worn a mercurial multitude of guises, disguises, and decoys (musical and otherwise) that have defined our times as much as they’ve defined him. Some of those shape-shifting forms and identities have been of his own shrewd, mischievous making, of course; others have been enthusiastically assigned by us, and occasionally reluctantly accepted by him (usually with an accompanying shrug): Populist Poet. Court Jester. Philosopher King. Pop Royalty. Protest Singer. Rock & Roll Recluse. Professional Obfuscator. Private Truth-Teller. Wounded Romantic. Born-Again Believer. Sarcastic Skeptic. All and none of them Bob Dylan.

Bob Dylan can get pretty cold: Dylan in ’66 by Jerry Schatzberg

Here at the “RPM” home office, I’ve been listening at length to the latest in the ongoing Dylan official bootleg series entitled, “Bob Dylan 1965-1966: The Cutting Edge” (Columbia), which, depending on the degree of your interest or budget, can span either two or six CDs, or a 3-LP version of highlights. What’s striking to me in hearing all of this music, culled from the well-traveled territory of my favorite Dylan era, is how so many genuine surprises of sound, thought, and expression abound half a century after the fact. The chrome sheen of that “thin, wild mercury sound” as Dylan once dubbed it, still gleams with liquid possibility and transformative promise.

SCARF & CIGGIE: Bob ponders his maximum cool, ’66

Much like the extravagant “Basement Tapes” box set that came out two years back, “The Cutting Edge” is a treasure trove of panoramic scope and obsessive detail aimed at more than the casual listener. But you don’t have to be a Dylan diehard to appreciate, or at least be startled by, what Bob’s first decade as an artist meant to music — his own and everyone else’s around him. To hear the fertile full-bloom and wild blossoming of his untamed talent is simply astonishing to take in, even on a cursory and purely visceral level.

Blowin’ Minds In The Wind: Who needs a leopard-skin pillbox hat when you’ve got hair this good?

If so inclined, we can certainly delve deeper into discussion, rumination, and analysis (and have, as the not inconsiderable cottage industry of Dylan scholarship attests).  In fact, we can go as deep as we want because, happily, we’ll never finally, truly get to the bottom of  it all (whatever that “bottom” may be). There’s no ground floor, and too many trap doors.

But “The Cutting Edge” invites us to eavesdrop on what was going on behind the keyholes in those fantastical rooms of 1965 and 1966. To hear Dylan’s lyrical ideas and melodic inspirations unfurl like slow flags or explode like fast fireworks, to listen to the songs spring to unruly life, you get a sense of what it might have been like to watch Van Gogh mix his colors and apply the bright yellows and brilliant blues to the swaying sunflowers and starry nights he dreamt into being.

DYLAN DREAMING: Or summoning the next couplet, 1966

That’s when something strange and euphoric happens. Our ingrained sense of the familiar, our internalized acknowledgment of a known masterpiece — the sense-memory meditation of “Visions of Johanna,” say — is  suddenly rendered improbably fresh and new again, a virgin vision. And just like that — right before our eyes, our ears, the senses we didn’t know we had — we’re hit with something like the blinding flash of an electrical storm. A bolt from beyond lights up the deepest corridors of our being, striking our synapses, our souls, our brains, our guts. And those are only the levels we know about.

Dylan’s music and what it does to us — why that perplexing, peculiar alchemy of voice and rhyme wrapped around rhythm (or is it the other way around?) should resonate so strongly — defies simple logic or conventional wisdom. For there is nothing conventional or straightforwardly logical about Bob Dylan in 1965-66. The man, his music, and his genius are both instantly recognizable and ultimately unknowable,  a magnificent mystery beyond our grasp.

Halo of Hair: Dylan’s holy aura under the stage lights ’65-’66.

But it’s a mystery that, however inscrutable, nevertheless speaks its own language boldly, directly, and eloquently. Like Dylan himself, it’s a tangle of contradictions that work in unpredictable ways. It’s music that meets our gaze, and challenges it.  To me, that’s the power and essence of meaningful art, and it’s the dichotomy and magic at the heart of Dylan’s best and most enduring music.

These days, I’ve found myself continually caught off-guard while listening to “The Cutting Edge,” struck by the ancient, un-heard wonders that resided within the walls of those fantastical rooms. But I’ve also wondered why, at this stage of the game, any of us should be startled or taken aback by the music, or expect anything less than an electrical storm or two. After 50 years, give or take, we should be used to Bob Dylan’s surprise lightning bolt surprises.