Sargent had become interested in spiritualism shortly after the Civil War, if not sooner, and published at least three books on the subject. A psychic named Dr. Watkins, presumably Charles Watkins, brought together several men at Sargent's home. He put two blank slates face-to-face and asked the men to hold on to the edges while placing a piece of pencil between them. They heard the pencil scratching and were surprised to see after a moment that messages had been written on the slates. As the participants said in a co-authored statement, "We all distinctly heard the pencil moving, and on opening the slates found an intelligent message in a strong masculine hand, in answer to a question asked by one of the company." The incident was repeated with brass locks on the slates; this attempt revealed a woman's handwriting.
Dr. Watkins and Epes Sargent, then, were using a rather unique form of automatic writing to communicate with spirits. Sargent was convinced enough by the "experiment in psychography" that he reported it in his last completed book, The Scientific Basis of Spiritualism, published in 1880. Sargent admitted in his preface that putting the two concepts together would be offensive to some people. But, he says, a true scientist must admit that he does not know all the laws of nature and the universe and must accept that there are forces he can never fully understand. He notes:
The credulity of unbelief threatens new dangers. By dismissing the phenomena as impossible, unnatural, or supernatural, specialists in science, — who, however eminent in their own departments, are ignorant of the first rudiments of the psycho-physical science, now inchoate,— instead of checking superstition by their scornful attitude, are really giving it its excuse for being. Persons experimentally sure of the phenomena, finding that they can get no guidance or light from men of science, qualified by laborious study and experiment to explain the occurrences, either put premature constructions on what they witness, or yield a too hasty credence to the assurances of some medium or medial pretender claiming a divine or high spiritual inspiration...
But the time has gone by when the facts of this volume could be dismissed as coincidences, delusions, or frauds. The hour is coming, and now is, when the man claiming to be a philosopher, physical or metaphysical, who shall overlook the constantly recurring phenomena here recorded, will be set down as behind the age, or as evading its most important question. Spiritualism is not now "the despair of science," as I called it on the title-page of my first book on the subject. Among intelligent observers its claims to scientific recognition are no longer a matter of doubt.