Doubt as to the eventual impact of one’s images has long been central for many of the most talented and committed observers. Even during that most visually explored of conflicts, the Vietnam War, the title of Don McCullin’s book of excruciating war imagery—Is Anyone Taking Any Notice? (1973), or The Destruction Business in the British edition (1971)—reflected the photographer’s enormous misgivings as to the efficacy of witnessing in media: misgivings, along with guilt, that still remain with him decades later.