To the Editor: We thank Dr. Hamilton for his comments on our case conference. We described a middle-aged man with no prior history of psychiatric illness who developed a paranoid schizophrenia-like psychosis for the first time at age 52. The onset of his illness followed a brief incarceration, although the symptoms continued long after his release. He had a past history of grand mal seizures between the ages of 15 and 29. Approximately 6 years after the onset of his illness, which was treated with antipsychotic medication, his symptoms remitted fully. Four years later, at the time of this report, he was functioning at his premorbid level. We compared this patient’s history to that of Sir Isaac Newton, who reportedly developed a paranoid psychosis de novo at age 51; all his symptoms remitted within 18 months. The main point of our case conference was that some types of late-onset psychoses expose the limitations of our current diagnostic systems and call for more research into the psychoses of late life.