This dissertation is the first systematic study of the development of Adolf Meyer's “psychobiological” psychiatry and its embodiment in the Phipps Psychiatric Clinic at The Johns Hopkins Hospital between 1908 and 1917. Medical historians have long recognized that the character of twentieth-century American psychiatry has been shaped profoundly by the influence of Meyer. His theory of psychobiology, however, was widely criticized as unreasonably empiricist and intellectually incoherent – impressions reinforced by his notoriously impenetrable published formulations of its principles. Historians have wondered, therefore, how such a nebulous and seemingly arbitrary theory could have exercised such a comprehensive influence on American psychiatry.

My approach to Meyer revolves around both an analysis of what structured his ideas and, importantly, an assertion that the power and coherence of those ideas emerge clearly in an analysis of their consequences for his clinical practices and scientific vision. I argue that two sets of principles valued by Meyer shaped his vision for psychiatry: on the one hand, his unwavering confidence in his notion of the scientific method rooted in the experimental and comparative approach of clinical-pathological research; and on the other, his conviction that the mind was involved in the biological struggle to adapt. For Meyer, two central propositions flowed from this. First, the pathological processes responsible for most forms of mental illness took place not at the level of tissues and lesions, but at that of adaptive behavior and individual experience. Second, despite its immateriality, pathological experience could be distinguished from normal experience in the same way the pathologist differentiated between diseased and healthy tissue – through “experiment” (in Meyer's particular rendering) and through the systematic and comparative analyses of large numbers of individual cases. Borrowing, then, from historian Frank Sulloway's conclusion that the fundamental conceptions of Meyer's better-known contemporary, Sigmund Freud, were biological by inspiration as well as by implication, I contend that, by the same criterion, the “Meyerian” model that so influenced twentieth-century American psychiatry was the creation of a Pathologist of the Mind.