This photo, which bounced around Twitter over the weekend, is not a photo of Bernie Sanders.

It appears to have popped up first on a page for Washington-based Sanders fans last week, credited to the friend of the original poster. "My girlfriend is on a flight from portland Oregon to New York," the caption read. "Guess who is seated next to her? Fast asleep, in coach. I love this guy."

But come on. It's not him. There are the tortoise-shell glasses (complete with cord so he can hang them around his neck) -- versus the solid-colored frames he normally wears. Maybe those are his plane glasses, you may think. Maybe before getting on a plane, he puts on his old glasses ... and a pocket square ... and grabs a fedora.

The campaign confirmed to The Post that the man pictured isn't Sanders, in case the evidence at hand wasn't obvious enough. But why did so many people (including some prominent ones) pass it around as though it was?

And here comes the take: This is a Sanders that his fans would expect. Flying coach -- and in the middle seat, no less. Tired, as in the first tweet, from his grueling presidential campaign. On his way to keep up the fight in another place.

Presidential candidates are often the canvasses for voters' projections. Donald Trump's many unorthodox comments and positions are hidden by what so many people want to see in him: A tough fighter who always wins. Hillary Clinton is a woman who has overcome obstacles and constant attack -- unless you're one of the many people who sees her as emblematic of a broken system, or worse. Sanders came into the election with the advantage that Barack Obama enjoyed in 2008 -- relative anonymity. When the canvas is blank, the projections come through much more sharply, as they did eight years ago.

Another example from over the weekend: The bird.

Cute, funny, sure. The campaign, recognizing a winner when it sees one, came out with this:

Shaping the projection. Elsewhere, Sanders fans turned the bird moment into Bernie-as-a-Disney princess and more.

The Internet plays a role how candidate projections are formed too, of course. Anything on the Internet that's mildly interesting becomes an overblown meme in 14 seconds flat. Take the example of the other sad-looking older gentleman from earlier this month, Sad Papaw.

Oh, you haven't heard of Sad Papaw? It was an old guy who made a hamburger dinner for his grandkids and only one showed up. A photo of him sadly munching a burger went viral. Over the weekend, he had a cookout in Oklahoma and people drove hours to eat his burgers.

This is how the Internet works. People felt bad for Papaw and shared his photo. He became every grandparent disappointed by a grandchild's failings, to which we can all relate. The Internet takes a projection from a Viewmaster and throws it on a big screen. Projects it on the moon.

And this is why a photo that is clearly not of a presidential candidate but maybe sort of seems like a presidential candidate can suddenly start spreading. We all want to vote for the candidate that comes closest to the ideal we hold in our heads. For many Sanders fans, a tuckered-out guy jammed into a lousy cross-country flight was a picture that they were happy to see.