For the moment, the Democrats have resumed their time-honored posture of arguing about trade policy. It’s an important issue, and one on which I’m not sure where I come down. But as they prepare to rip each other’s flesh, they might bear in mind it isn’t the issue. The issue, as I wrote two weeks ago in urging Hillary Clinton to go big, is wage stagnation. I offer this up as a timely public-service reminder: Remember, folks, what you agree on.

As I noted in the go big column, wages have been in essence flat for earners—up 6 percent (adjusted for inflation)—in the middle of the income scale since 1979. For the top 1 percent, compensation has risen about 140 percent since the fateful year. This needs to be the issue of this campaign. If American voters don’t know these 6 percent and 140 percent figures November 8 next year, Hillary Clinton and the Democrats will have done something very wrong.

Economists choose 1979 as the cutoff year because, looking back over the numbers, that’s when the flattening started. It’s also about when compensation at the top started soaring (a little later, actually). Until the early to mid-1980s, Wall Streeters and corporate lawyers and actors and university presidents and star athletes made more than the rest of us, but they didn’t make gobs more.

For example, the average baseball salary doubled, up to around $370,000, from 1981 to 1985. The average wage in that same time frame went from $13,773 in 1981 to $16,822 in 1985, an 18 percent increase. Not bad, better than average; but not double by a long shot. I’m not saying the juxtaposition of these numbers proves anything more than it proves. But it is certainly representative of what was happening to American wages then and has been happening since.

Another way of looking at it: The average ballplayer went from making about 12 times the average American to 22 times. Today, incidentally, it’s 108 times, $4.25 million to around $39,000.

So what we’re gonna do right here is go back, way back, as an old song had it, to the year of Apocalypse Now and Get the Knack and those hideous Pittsburgh Pirates uniforms that so offended my aesthetic sensibilities that I had no choice but to cheer against the team I’d grown up worshipping. Let’s ask: What if the wage structure in the United States today were the same as it was in 1979?

Larry Summers asked the question in the Financial Times back in January. The bottom 80 percent of earners, he wrote, would have $11,000 more per family, and the top 1 percent would have $750,000 less. In the wake of Summers’s column, the folks at NPR’s Planet Money took it one step further and calculated the increased (or decreased) income for households at several points along the wage structure. It’ll pop your little eyes.

The poorest wage-earners, at $12,000, would be making $3,282 more. That’s a 27 percent increase. Those at $30,000 would be making $6,928 more (23 percent). Those at $52,000 would be getting $8,752 more (16.8 percent). For those at $84,000, the increase drops off, to $5,834 more (7 percent). But it kicks back up for those at $122,000, to $17,311 (14.2 percent). And finally, those in the top 1 percent, at $1.41 million, would see a decrease in earnings of $824,844, or a whopping 58 percent.

Now before we go any further—no, no one today is talking about anything as confiscatory as wiping out 58 percent of the top 1 percent’s earnings. That isn’t how it’s going to work anymore, with top marginal tax rates of 76 percent (which does not mean that the government took three-quarters of someone’s money; go look up the concept of “marginal” if you don’t get this).

But the wage structure is a function of a whole host of other policies and practices that have nothing to do with marginal tax rates. It has to do, yes, with the minimum wage. It was $2.90 in 1979. Adjusted for inflation, that would be $9.38 today instead of the actual $7.25, which is a 23 percent decline for those workers, and minimum wage is generally thought to have knock-on effects at least a third of the way up the wage chain. It has a lot to do with corporate culture: In 1979, CEOs at the top few hundred corporations made about 28 times the average worker’s salary; now they make more than 200 times. There were 15.1 million private-sector union workers in the United States in 1979; last year, there were 7.35 million. And in 1979, Washington oversaw a lot more in public investment than it does today, and those dollars by and large went into real things, from bridges to scientific research, instead of swaps and derivatives.

Now, 1979 was a bad year in some important ways—inflation, hostage crisis—so I’m not saying I think it would be the world’s greatest idea for the Democrats to campaign on bringing back 1979. It’s not about the year per se. That just happens to be the year the thing started happening. And the thing is flat wages for most people who work for a living.

The trade fight has to be played out, and it seems that the unions and the Warren wing are probably going to lose, because the president will get enough votes from Republicans and moderate Democrats. And of course it’ll be interesting to see how Clinton plays it. Whichever position she takes, we can be sure she’ll do it cautiously.

So dust will be kicked up over that. It has to be. The differences are real. But comparatively, the differences are small. Democrats must keep their eyes on the prize. “Who cares more about increasing the wages of working Americans?” is a debate question the Republicans can never win. The Democrats have to make sure the election is about that question.