Tim Hetherington and Chris Hondros

I didn't know Chris Hondros. I took his brilliant photographs for granted, the way that most of us take photojournalism for granted. Of all people, I should have known better. With Tim Hetherington it was different, because I was personally familiar with the energy, conviction and talent that went into his work and with the dangers he faced. I edited his book Infidel, a group portrait of a platoon of U.S. soldiers at a remote outpost in Afghanistan. When Tim introduced his pictures to me, it was with compelling clarity and cause. "George Orwell said that we sleep peacefully in our beds because rough men are ready to do violence on our behalf," he told me. "I want to show people the lives of men we send out to do our dirty work."

Tim was a gifted storyteller, but he also pioneered how he got his work out into the world, using photos, video and commentary disseminated simultaneously via print media, cinema, books, art installations and social networks. "Transjournalism," he called it. I thought he was reinventing the language of photojournalism and beginning the period of his best work. If there's a moral to the deaths of Tim and Chris--who died covering the Libyan city of Misratah on April 20 at 40 and 41, respectively--it is that we must value more highly the work they risked their lives to bring us and, by extension, the work of their many brave and gifted peers.

Boot is the executive director of the Aperture Foundation