In 1861, while alone in a room, the Boston engraver William Mumler took a self-portrait, which after development showed the likeness of another figure. This episode launched what would become known as spirit photography, which lasted in popularity until the 1930s. Mumler later moved from his Washington Street studio to New York City, where he established a successful practice, charging as much as $10 and guaranteeing results. He was later accused of fraud and brought to trial. Although the case against him was dismissed, it hurt his reputation enough to lead him to destroy most of his negatives.

The seemingly strange phenomena of Spiritualism and spirit photography can teach us a lot about how photography was and still is conceived. Interestingly enough, the language of photography's inventors and its cultural reception, as many critics have pointed out, was distinctly otherworldly. These two ontological roles of photography occurred simultaneously, without necessarily contradicting one another. Even today, photography continues to explore the farthest regions of the universe (most recently with images from Mars) and phenomena we could never "see" with our naked eyes.

An American product of the modern age, Spiritualism's history is riddled with stars and starlets, with its supporters tried in court and governmental hearings. At the same time, it counted among its followers some of the finest minds of its day, well-known personalities, scientists, and authors. (Even the women's movement and politics had a voice in Spiritualism, as most mediums were females of the radical persuasion.) The movement that would eventually claim over 12 million followers had its humble beginning in the small upstate New York town of Hydesville. In 1848, two sisters, Katie and Margaret Fox, claimed to have communicated with the spirit of a murdered peddler buried under their house. Using an elaborate system of knockings (which one sister later explained were their toe joints cracking against the bedposts), they could answer "yes" and "no" to questions, a sort of spiritual version of Morse code. Soon after their fame, the sisters moved to Rochester—coincidentally, as one writer noted, the city that what would later become the home of two major imaging companies, Eastman Kodak and Xerox.

Audiences and visitors to this exhibition might ask: How can anyone take the historical images (some of which seem obvious products of double exposures and composite printing) seriously? Notwithstanding, we could just as easily ask ourselves why, even in the face of tremendous advances in science and technology, the human psyche is still entranced by the paranormal and its attendant proof. Such swirlings of prophetic photographs as well as an interest in the afterlife seem to proliferate after war or societal strife. It is no coincidence then that spirit photographs appeared after two of periods of extreme casualty and duress: the Civil War and the First World War. (One of the most famous spirit photographs was Mary Todd Lincoln embraced by the specter of her assassinated husband.) September 11 saw its own series of manipulated images—a displaced attempt to comfort the masses and make sense of tragedy.

Spirit photography still finds an audience today as evidenced by the hundreds of amateur ghost hunter websites showcasing various ethereal looking blobs, streaks, orbs and vortexes. Indeed, many of us have yielded something similar on a roll of film, usually explained away as light leaks, x-rayed film, a camera strap, or mist or smoke in the air. At the same time, there always seems to be one small effect, one strange occurrence, that eludes even the experts, fueling the fire and leaving the door open for continued belief. Therein lies the enigma of photography.