Most of us who have lost most of our hair … we’re pretty much the last to know. Or the last to accept it.

“I’ve got plenty of hair over here. I can just stretch it across …”

No, really, you cannot. And when you reach the point where you are desperately trying to make hair from the sides of your head cover the crown (looking at you, Mr. President) … it’s time to give it up.

But we don’t give up easily, do we? If we can deny it … maybe the erosion of hair will stop.

And as an example I present to you a Russian conductor, who really ought to know how sad his comb-over looks, particularly when he is sweating at the podium — and he seems to be sweating by about the 10-minute mark of any performance.

Let’s find some proof of that.

Here is our man, Valery Gergiev, a Russian director thought to be a favorite of the Russian president, Vladimir Putin.

Check the opening seconds of this performance of Tchaikovsky’s “Romeo and Juliet.”

There’s our guy and his comb-over. Already it looks shaky, and the orchestra hasn’t played its first bar.

At the 9:15 mark, the idea that he has hair atop his head has been revealed as a fiction.

At the 15:50 mark, his heavy sweating is overpowering whatever gel he might have put on those hardy survivors of his hair line.

At the 19:40 mark, we reach the final chords, and the only question now is what is a more believable story — Shakespeare’s Romeo and Juliet or Gergiev’s comb-over.

What makes it worse comes at the 19:50 mark, after the piece is finished. First thing Gergiev does …. the first thing … is drag a chunk of sweaty hair over the emptiness of his pate.

This is a man deep in denial. I suggest the buzz cut, Valery. Own it!

Could try a hairpiece, but everyone will notice … probably too late for hair plugs, though someone certainly will do them for you, plus you will have to hide out for several weeks, as the hair tries to take root. Or wear a lot of baseball caps; that works for me. (Ha.)

And if you think that this particular performance stands alone among Gergiev’s oeuvre … well, no.

Here is another. Same thing, maybe worse, because he’s even sweatier.

Scheherazade by Rimsky-Korsakov, and this one lasts 42 minutes.

Observe the situation at 29:30. Not going well. And this performance came in 2005, two years before his Romeo, when he was 52 instead of 54 … and we can imagine Gergiev, like many of us, only beginning to think, “Hmm, I wonder if anyone notices my hair is thinning just a bit.”

Ah, but check the brave comb-over as Gergiev comes on stage. “That will fool them, Valery! No one will notice! Your dignity and your follicles remain intact!”

Then you’ve got the indisputable facts of a lack of coverage at 37:15 and thereafter … and again, at the end … the instinctive push of long thin hair back to its role of covering a square yard with about 200 strands.

As regards Gergiev, we could talk about many other things. His reputation, his politics, his competence, the instructions he sends to musicians in strange and unfathomable ways. (The fluttering hands with wiggling fingers is one of his favorites; it looks like a disturbed version of “jazz hands” and means … who knows what.)

But, end of day, the comb-over is what even a generous spirit takes from the conductor’s performance.

Not because we are mean, but because it is so vain and so obvious — and so familiar to those of us who have been there.