Alexander Crichton’s Inquiry (1798) was one of the first systematic English-language works on mental disorder. Although a general physician rather than a specialist, Crichton sought to explain how emotions, attention and the nervous system interacted to produce disturbance. His description of inattention is now regarded as the earliest English medical account of what we would call an attention disorder. He drew extensively on German case reports, vivid accounts of melancholy, delusion and violence. He highlighted how delusion could coexist with calm, purposeful behaviour, influencing both medical and legal views of responsibility. Modern historians see Crichton as a synthesiser rather than an originator, but his Inquiry remains an ambitious attempt to ground the study of mental disorder in physiology, observation and compassion.