My main job these days is helping to bring in collections of photographs for the archives at the Center For American History at the University of Texas in Austin.

The Center has built the most important collection of American Presidential Photography in the world. These photographs, taken by photographers such as David Hume Kennerly, Diana Walker, Arthur Grace and Wally McNammee, together with their captions, stories, notes, and memorabilia will be available for future generations to study.

I once watched David Rubinger, the dean of Israeli photography berate a hapless young photographer who had thrown unprotected rolls of processed film from a story into a pile in the trunk of his car.

"How dare you!" Rubinger yelled. "Don't you realize that is the history of our land that you are putting at risk!" Rubinger knew what he was talking about.

This one man had personally photographed every major event, personality and battle since the birth of Israel as a state. His collection, which has been meticulously cataloged by him, is the most important archive that the country has. Several years ago, he received Israel's highest civilian honor for what he had personally done to record and preserve the visual legacy of Israel.

Now that I am in my 60s, and in the process of preparing a retrospective on my work, I sometimes get sick thinking of photographs I have discarded or lost over the years. There is, for example a photograph of Richard Nixon pacing the deck of the Presidential yacht, The Sequoia, on the night he decided to resign, that only I had photographed. The Time picture editor returned those negatives to me long ago when they were cleaning out some files, and I have no idea what I did with them. I would pay thousands of dollars today to find that picture. It is a truism that when you are young, you have little idea of the consequences of your actions in years to come.

The most banal of photographs when looked at 100 years later have lives of their own.

Just think of all the times you have looked at photographs hanging on the wall of a restaurant or bar of street scenes taken early in the 20th century. Who would have guessed that a photograph of a couple of people standing on a street corner, doing nothing in particular would have the power to mesmerize future generations?

If I had, like the wire photographers erased the photograph of Monica Lewinksy hugging Bill Clinton from my hard drive, as the other photographers who were there that night did, there would be no visual evidence in existence of that moment, which helped to decide the legacy of a President. We still don't know the long-term implications of what that moment captured in time will have in years to come.

As photojournalists we have not only the privilege of witnessing history, but we also have the responsibility of saving it.