California State Senator Scott Wiener, a Democrat representing San Francisco, is an avowed progressive who has come up with a startling new doctrine to advance his leftist cause—the law of supply and demand.

For sure, Wiener is nobody’s idea of a conservative or right-winger. He ticks the lefty box on everything from recycling to transgender rights to opposing tax cuts. So why, then, was Wiener’s recent housing legislation, Senate Bill 827, fiercely opposed by the Sierra Club, which was joined by other progressive groups? And why was it voted down by Wiener’s Democratic colleagues in Sacramento?

The answer to those questions reveals a deep split not only in the Democratic Party, but also in the left overall. To put the matter bluntly: should progressivism serve the masses or the elites? Today, the elites are enjoying the lion’s share of progressive gains—and that’s what Wiener wants to change.

Wiener’s bill was aimed at addressing a crisis in his city: the lack of affordable housing. Today, the median home price in San Francisco is $1.6 million, about eight times the national median. The principle cause of this price inflation is the mismatch between the demand for housing and the supply of housing. That is, the surging digital economy has supercharged demand, while tightening limits on construction have enervated supply.

To be sure, the phenomenon of grossly unaffordable housing is larger than just in San Francisco; it extends to the entire Bay Area. Earlier this month, for example, a house in the once-dowdy East Bay town of Fremont, condemned as uninhabitable, nonetheless sold for $1.2 million. Of course, the tattered home will soon be torn down—it’s the buildable land that’s precious. In the words of Tendayi Kapfidze, chief economist at LendingTree: “The Bay Area has among the most restrictive building environments for new homes in the country, thus the increase in supply has lagged far behind the rising demand. As a result the market finds equilibrium by boosting prices and pushing some potential buyers out of the market.”

In fact, most potential buyers are pushed out of the market. In the Bay Area, workers are frequently pushed out beyond the suburbs, beyond the exurbs—all the way to other cities. And so commutes of two hours or more are common.

Wiener’s bill would have addressed this problem by partially overriding local zoning restrictions on housing density, specifically on height limits, in areas served by mass transit. It’s hard to think of a bill more friendly to the masses than that. Yet Wiener ran into a wall of liberal Democratic opposition—the vice mayor of Beverly Hills was a particularly vocal opponent—and thus the bill died on April 17.

Why the fierce opposition? Perhaps it’s because the dominant progressive voices in California are, in fact, regressive. That is, they prefer to protect the privileges of the landed—who benefit, of course, from high land prices—as opposed to the aspirations of the landless.

In history, such behavior is nothing new. Indeed, with historical continuity in mind, urban analysts Joel Kotkin and Fred Siegel back in 2007 coined the term “gentry liberalism” to describe this age-old phenomenon.

Gentry liberalism recalls the aristocratic, even feudal, days of yore when the lords in their estates didn’t wish to be crowded by the bourgeoisie, to say nothing of the peasantry.

To be sure, modern political niceties prevent the lords and ladies of today from pronouncing that they wish the rabble to be gone. And so the exclusionist argument is laundered through the green vernacular of “sustainability.” It’s by this linguistic transmutation that the selfish NIMBY (Not In My Back Yard) activist is elevated into a high-minded eco-hero.

It’s fair to say that this gentry liberalism—that is, greenwashed NIMBYism—is the dominant ideology in California. Bolstered by big money from tech gods and trust funders, gentry liberals have simply bought the state’s politics.

The impact of gentry liberalism is visible in a national “heat map” of real estate prices. Indeed, the pricing of coastal California—from the Bay Area to the Mexican border, and fairly far inland, too—is so hot that it’s out of reach for the proles. In Los Angeles, for instance, the typical home costs $553,000; only one in four Angelenos can afford to buy there.

In other words, the bulk of California’s 39.5 million people are finding themselves squeezed out of normal home ownership. Thus the plutocrats get their oceanfront views, while their maids and gardeners are forced to live far inland, 40 or 50 miles away. Moreover, an increasing number of California’s gainfully employed are forced to live in their cars. In fact, thanks to gentry liberalism, when adjusted for the cost of living, California has the highest poverty rate in the nation.

In response to these baleful social trends, gentry liberalism has one surefire response—it moves further left. Further left, that is, on symbolic issues such as climate change or sanctuary cities; the hope is that Californians will be so intoxicated by ideology that they won’t take sober notice of their material condition.

Why, it’s almost enough to make one think that the ancient Roman tactic of “bread and circuses” has been revived—revived progressively, of course. Today, the diversionary entertainment for the masses isn’t gladiators attacking each other in the arena but California politicos attacking Donald Trump on television.

Then along came Scott Wiener to threaten this gentried-up arrangement. His argument could be stated simply: my constituents need affordable housing, so let’s change the law to allow the building of it. Wiener was making, in its essence, a class-based argument—the teeming masses, too, deserve a piece of the pie.

Indeed, in its class starkness, one can hear still more classical echoes. In ancient Rome, the plebeians plotted against the entrenched aristocratic power of the optimates; these days, the plebs of San Francisco have organized themselves into the YIMBY (Yes In My Back Yard) Party. As they declare in their platform, “We strongly support building new housing. …Increasing supply will lower prices for all and expand the number of people who can live in the Bay Area.” And then the YIMBYs add a populist poke: “We should build more housing in every neighborhood—especially high-income neighborhoods.”

Wiener and the YIMBYs have found plenty of support on the non-gentry left. For instance, Markos Moulitsas, the East Bay-based publisher of Daily Kos, put his sharp pen to the task when he wrote of the NIMBYs, “In common political parlance, this effort to lock in the status quo on behalf of the wealthy, and to prevent change at all costs, would be considered ‘conservative.’” And so, he continued, “It is genuinely ironic that it’s so-called ‘progressives’ driving such restrictions.”

So would Wiener’s plan, if enacted, actually work? Would fewer restrictions really lower housing prices? Common sense tells us that greater supply would indeed level off prices. And yet if we need more reassurance, we can turn to Bloomberg News’s Noah Smith, who notes that the YIMBY approach has worked where it’s been tried. Tokyo, for example, is a city of more than 13 million people, and yet its housing costs are half those of San Francisco. And the reason is simple: Tokyo has continued to build housing at a much faster pace than other big cities. So there you have it: markets work. If you let supply rise to meet demand, prices will equilibrate. It’s Adam Smith 101.

For his part, Wiener isn’t likely to cite Smith, but he vows to keep pushing. Indeed, he has even used language that opens the door to bipartisan cooperation: “I will continue to work with anyone who shares the critical goals of creating more housing for people in California.”

So that raises an interesting question: are Golden State Republicans interested in working with Wiener? During the recent fight over SB 827, the Cal GOP was studiously muted, more focused on traditional issues such as lowering taxes. But could Republicans, the one-time party of the optimates, now pushed to the margins in California, find new vigor as a party for the plebs? That is, after all, the direction pointed to by Donald Trump at his populist best. Now we’ll have to see if other Republicans are interested.

History tells us that the masses, when mobilized, have a fair shot at prevailing in their class struggles—including, these days, the fight over housing. That is, since the potential winners from YIMBY far outnumber the current winners from NIMBY, the Wiener Army might yet surmount the barricades.

In the early 19th century, the poet Shelley did the math for rising British proletarians: “Ye are many—they are few.” And in the century to follow, Britain was reformed—and transformed.

Today, in the early 21st century, the same numerical ratios beckon American proletarians. Yes, housing in California hangs in the balance. But so, too, does the course of American history.