I once went to Washington for what they call a “photo opportunity” with Henry Kissinger. As I led him to the camera, he said a puzzling thing. He said, “Be kind to me.” I wish there had been time to ask him exactly what he meant, although it’s probably clear. Now, Kissinger knows a lot about manipulation, so to hear his concern about being manipulated really made me think. What did he mean? What does it really mean to “be kind” in a photograph? Did Kissinger want to look wiser, warmer, more sincere than he suspected he was? Do photographic portraits have different responsibilities to the sitter than portraits in paint or prose? Isn’t it trivialising and demeaning to make someone look wise, noble (which is easy to do), or even conventionally beautiful when the thing itself is so much more complicated, contradictory, and therefore fascinating? Was he hoping that the photograph would reveal a perfect surface? Or is it just possible that he could have wished – as I would have if I were being photographed – that “being kind” would involve allowing something more complicated about me to burn through: my anger, ineptitude, strength, vanity, my isolation. If all these things are aspects of character, would I not, as an artist, be unkind to treat Kissinger as a merely noble face? Does the perfect surface have anything to do with the artistic integrity of a portrait?

A photographic portrait is a picture of someone who knows he’s being photographed, and what he does with this knowledge is as much a part of the photograph as what he’s wearing or how he looks. He’s implicated in what’s happening, and he has a certain real power over the result. The way someone who’s being photographed presents himself to the camera and the effect of the photographer’s response on that presence is what the making of a portrait is about. The philosopher Roland Barthes once said a very wise thing about photography. He said, “Photography is a captive of two intolerable alibis. On the one hand, ‘ennobled art pictures.’ On the other hand, ‘reportage’ which derives its prestige from the object. Neither conception is entirely correct.” He said, “Photography is a Text, a complex meditation on meaning.”

What Barthes recognized is that we need a new vocabulary to talk about photography. Not “art” versus “reality,” “artifice” versus “candor,” “subjective” versus “objective” photography falls in between these classifications, and that’s why it’s so impossible to answer questions like “Is photography really art?” and “Is this an accurate picture of your friend?” As I have said on other occasions, “All photographs are accurate. None is the truth.”

I don’t think pictures have to justify their existence by calling themselves works of art or photographic portraits. They are memories of a man; they are contradictory facets of an instant of his life as a subject, and of our lives as viewers. They are, as Barthes said, texts, and as such, they exist to be read, interpreted and argued over – not categorised and judged.

So who is Henry Kissinger? And what, or who is this photograph? Is it just a shadow representation of a man? Or is it closer to a doppelgänger, a likeness with its own life, an inexact twin whose afterlife may overcome and replace the original?

When I see my pictures in a museum and watch the way people look at my pictures, and then turn to the pictures myself and see how alive the images are, they seem to have little to do with me. They have a life of their own. Like the actors in Pirandello, or in Woody Allen’s movie The Purple Rose of Cairo, when the actors leave the screen and join the audience. They have confrontations with the viewers. Photography is completely different from every other form of art. I don’t really remember the day when I stood behind my camera with Henry Kissinger on the other side. I’m sure he doesn’t remember it either. But this photograph is here now to prove that no amount of kindness on my part could make this photograph mean exactly what he, or even I, wanted it to mean. It’s a reminder of the wonder and terror that is a photograph.