As his campaign for president gathered steam, Sen. Bernie Sanders (I-Vt.) went on CNBC and challenged the business news network’s audience.

“You can’t just continue growth for the sake of growth in a world in which we are struggling with climate change and all kinds of environmental problems. All right?” he said. “You don’t necessarily need a choice of 23 underarm spray deodorants or of 18 different pairs of sneakers when children are hungry in this country. I don’t think the media appreciates the kind of stress that ordinary Americans are working on.”

What a surprise, then, to learn last week that the Bern and his wife, Jane, have determined that what they need is a third piece of residential real estate.

To go with places they already own in Washington and their home town of Burlington, Vt., the Sanders family has purchased a vacation home on an island in Lake Champlain. Price: $575,000, nearly triple the average cost of a house in the Green Mountain State.

Gotcha! cried a chorus of hypocrisy-spotters — including not only the Bern’s usual critics on the right but also a few disappointed democratic socialists.

Senator Bernie Sanders (I-Vt.) made waves as a democratic socialist presidential candidate. Here’s what you need to know about being a democratic socialist and how it’s different from socialism. (Alice Li/The Washington Post)

No argument here: As a slogan for the political revolution, “from each according to his ability, to each according to his need for lakefront property” doesn’t really cut it.

To be sure, as limousine liberals go, the Sanderses hardly represent a flagrant case. They’re far less wealthy than — to pick a well-heeled lefty pretty much at random — Rep. Nancy Pelosi (D-Calif.), whose reported fortune tops $74 million . Nor have they cashed in on their political careers with the zeal of a Bill or Hillary Clinton.

If anyone profited from Sanders for President, it was the political consultants, who billed the campaign (and, by extension, its small-donor network) millions of dollars for TV commercials — which trashed millionaires and billionaires, and marketed the Bern like a brand of underarm spray.

Bernie may be a dreamer, but Jane Sanders is an astute negotiator who exited her seven-year stint as president of tiny Burlington College with $200,000 severance in 2011, notwithstanding the declining enrollment and mounting debt that marked her tenure. She was ready with a pragmatic rationale when the media asked about the third home buy: It was partly about updating her modest inherited real-estate portfolio, and partly the fulfillment of a long-standing wish.

“My family had a lake home in Maine since 1900, but we hadn’t had the time to go there in recent years — especially since my parents passed away,” she said. “We finally let go of it and that enabled us to buy a place in the islands — something I’ve always hoped for.”

All told, what’s instructive about this episode is not the extravagance of Bernie and Jane’s materialism but its relative modesty.

Theirs is not the greed of a billionaire class. It’s the garden-variety acquisitiveness of the upper middle class, fostered by government through deductions for mortgage interest and state and local taxes, both of which benefited the Sanderses, according to their 2014 income tax return (the only one they’ve released).

If even people as dedicated to equality and social justice as Bernie and Jane Sanders — and with as much to lose by appearing not to be — can succumb to material desire, that suggests it’s a hard-wired aspect of human nature, not a uniquely capitalist evil.

Accordingly, it’s a myth to imply, as Sanders so often does, that the engine of capitalism is corporate greed — as opposed to the widespread, and perfectly natural, human desire for more, better, different.

Capitalism channels those impulses to productive ends. The result has been immense economic growth, the fruits of which have helped the United States to clean up its environment and feed its children, contrary to Sanders’s outburst on CNBC.

Still, he prefers socialism, which, even in a “democratic” variant, posits that there are appropriate targets for both production and distribution, and that government can enact them.

As history shows, this notion has its pluses and its minuses, but surely one of the latter is the difficulty of objectively differentiating between acceptable greed and the other kind.

One person’s hope for a place in the islands could be another person’s “worship of money,” to borrow a phrase from Sanders’s declaration of democratic socialist principles in November . It’s intrinsically perilous to endow government officials, even elected ones, with discretion over such questions.

Here’s a thought for Sanders to ponder, as he settles into his Adirondack chair. There’s plenty to dislike about the status quo in the United States. But it did guarantee him a right to the share of resources he considered affordable and justified, no matter whose high-minded princples that might contradict — even his own.

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