Photography is an elegiac art, a twilight art. Most subjects photographed are, just by virtue of being photographed, touched with pathos. An ugly or grotesque subject may be moving because it has been dignified by the attention of the photographer. A beautiful subject can be the object of rueful feelings, because it has aged or decayed or no longer exists. All photographs are memento mori. To take a photograph is to participate in another person's (or thing's) mortality, vulnerability, mutability.
Susan Sontag,On Photography,1977.