All three Democratic candidates favor raising the minimum wage up to somewhere between $12 and $15 an hour. But forget, for a moment, the minimum wage—what about establishing a maximum wage?

It’s a question that no candidate is asking at the moment, but it’s one Bernie Sanders used to be preoccupied with, starting in the 1970s. Back then, during one of Sanders’s early Senate campaigns, one local Vermont newspaper wrote that he wanted to “make it illegal to amass more wealth than a human family could use in a lifetime.” Sanders was apparently still batting the idea around until at least the early ‘90s, when he submitted a Los Angeles Times op-ed by the journalist Sam Pizzigati titled “How About a Maximum Wage?” to the congressional record. (The Sanders campaign has been contacted for comment but has not yet replied.)

Here’s how it’d work: Right now, any dollar an American earns beyond a certain amount (about $450,000) is taxed at 39.6 percent. This is America’s top marginal tax rate, and lower marginal tax rates are applied to money earned under other lower thresholds. Sanders’s one-time plan for a maximum wage was simple: Set a threshold above which the marginal tax rate is 100 percent, so that every dollar earned beyond it would go straight to the government.

Sanders has since scaled back his vision. He hasn’t revealed the specifics of his tax plan, but he’s said that his proposed top marginal tax rate will be somewhere between 50 and 90 percent. (Ninety percent, as Sanders has pointed out, is about what the top marginal tax rate was during the tenure of Dwight Eisenhower.) Today, a top marginal tax rate of 100 percent is such a radical proposition that there hasn’t been much academic writing about it (though a British economist supported the idea in a paper 10 years ago).

Decades ago, the notion of a maximum income had much more mainstream support, even if it never really stood a chance of becoming law. In the ‘40s, Franklin Delano Roosevelt recommended instating a maximum income, prompting one famous actress to say publicly, “I regret that I have only one salary to give to my country.” Congress, however, was less enthralled, and it declined to approve Roosevelt’s proposed cap on net income at $25,000, or about $365,000 in today’s dollars.

Sanders, of course, said and wrote many things several decades ago that he doesn’t believe now. One of his pieces published in alternative Vermont newspapers in the ‘70s, as noted by Mother Jones earlier this year, suggested that it isn’t all that unnatural for humans to eat the placenta in a ritual after birth. Other essays he wrote around that time drew attention to the (completely bunk) correlation between “the manner in which you bring up your daughter with regard to sexual attitudes” and “whether or not she will develop breast cancer.”

But while the specifics of Sanders’s economic message may have changed over the years, he has remained true to certain core values. A 1974 newspaper article reporting on his political platform was headlined “Concentrated Wealth is Causing Economic Illness,” a phrase that would not be surprising to hear from Sanders at a debate these days. As Paul Heintz, the political editor of Vermont’s Seven Days recently told the podcast On the Media, “He has been making the same point for 40 years.”