Do Jimmy and Jonesy realize...?

Robert Plant's entire professional career has been one of constant evolution. When Led Zeppelin evolved as a band, Robert evolved as a singer. When Led Zeppelin broke up, Robert found new ways to branch out. When he made peace with his past, he discovered ways to redevelop the music of his past while never failing to forge new territory ahead.

Jimmy Page and John Paul Jones must be cognizant of this; after all, they're in the middle of it all. They're more aware of it than is any hack who's typing up opinions on a BlackBerry after a day's work in Washington, D.C., right?

But exactly how deep is their appreciation for how far Robert has come in the 28 years since Led Zeppelin ceased functioning as a creative force?

How many times do you think they have spun Robert's album with Alison Krauss to know what Raising Sand is all about? How many shows have they caught on their tour, which went to the United Kingdom last week?

Think either has watched enough Strange Sensation videos over the past eight years to understand Robert's passion in the Dreamland and Mighty ReArranger albums?

I don't think it's appropriate to consider the possibility of any future Led Zeppelin activity without fully comprehending the disparate personalities involved and the places in which those people must find themselves, and each other.

Any modern-day, full-length Led Zeppelin concert would, by all expectations, necessarily have to be more like that concert in London last December than any show before it. It's just natural and proper to assume this.

That means the inevitable numbers cannot be pulled. And we all know which ones those are. The band would be forever maligned if any of the following five did not make it into the set list of a 2008/2009 show: "Black Dog," "Since I've Been Loving You," "Dazed and Confused," "Stairway to Heaven" and "Whole Lotta Love."

Dare to put on a Led Zeppelin concert without those at this time, and nothing would be closer to professional suicide. Somebody, somewhere, would paint Led Zeppelin as irrelevant old folks who don't know how to pander to the masses when that's what they should be doing.

So, half your set list has already been dictated by popular demand. That much is set in stone.

Sure, save for "Dazed," these songs never dropped from Zep set lists once they made it into the live act. And Page, Plant, Jones and Jason Bonham had no problem playing them back then. They were in charge.

Someone at or near age 60 deserves better than to be told what to do. It must be frustrating when that happens.

On top of that, it's probably true that there are many songs a modern-day Led Zeppelin concert should ignore. Basically, anything not performed by Led Zeppelin by 1980 falls into that category.

Plant, Page and Jones have been fond of working cover songs into their own live sets and onto their solo albums since then. But it would be seen as heresy for Page to insist on adding Fleetwood Mac's "Oh Well" to a Zep set, or for Jones to demand "Down to the River to Pray" stuck in between a couple of acoustic songs.

This is especially more challenging to Plant, who has never shied away from a good cover.

I mean, you can play "We're Gonna Groove" and "Gallows Pole" and "In My Time of Dying" at a Led Zeppelin concert. Even though they're (basically) covers, they're fair game because the original Zeppelin touched them.

But two of Plant's three most recent albums have been almost entirely made up of covers. Led Zeppelin never played songs by Gene Clark, Arthur Lee, the Everly Brothers, Stephen Stills or Skip Spence, so there are an awful lot of cover songs he favors that wouldn't quite fit into a Zep show.

Not only that, but it's also natural that Led Zeppelin shows would force the band members to ignore performing any songs from their outside projects. Who stands to suffer the most from this? Again, it's Plant, who since 1980 has taken part in eight albums of new material.

Imagine a Led Zeppelin concert that ignores Page's unremarkable solo album, Outrider, and any of the work by his other bands, the Firm and Coverdale/Page. Totally believable and appropriate, isn't it?

What are you giving up by ignoring JPJ's solo work? Mostly some great instrumentals spread across three albums.

Ignore Robert's post-Zep career in a concert, and there's a whole lot more auspiciously missing.

He went out and played some shows like that in 1998, playing to the big houses with Jimmy Page, and note how Plant ended up pulling the plug by the end of the year.

Tell Robert he isn't free to reproduce certain material onstage, and you may have yourself a dealbreaker, folks.

It is these factors that make a Led Zeppelin show seem restrictive to the creative process and to future evolution.

Fans who argue Page, Plant and Jones ought to write new material are kidding themselves if they think new songs will be given a fighting chance in a live setting. No matter how good it is, it would still be deemed a bathroom break. There's no room for a bathroom break in the Led Zeppelin legacy.

All in all, the band's own legacy is the hindrance that may keep the group from reforming yet again. It stands to be tainted.

The uneducated rumor mill says Led Zeppelin will be touring soon. And further, Whitesnake is opening for them. I'm going to laugh myself silly. There's absolutely no way this story has any credibility today.

And the money? Please. That won't change Robert's mind. Not now, not ever. "Tour" is a bad word. Maybe Led Zeppelin would agree to play a few charity events, but probably not more than about eight. He definitely isn't interested in the "T" word. It's just not about the money.

Personally, I don't see how a Led Zeppelin reunion could be anything more than just a few charity benefits and a huge commitment.