Diagnosis is arguably the most important job of a physician. But what does it actually mean to make a diagnosis? In this episode, we’ll explore this question by tracking the development of the “classical” model of diagnosis and pathological anatomy and discussing three cases over three hundred years. Along the way, we’ll ponder the concept of the lesion, iatromechanistic theories of the human machine, the birth of the International Classification of Diseases, and the rise and decline of the autopsy.