Empathy has been studied in composition since the 1960s, although it has not yet been adequately defined or theorized. Compositionists tend to employ the common definition of empathy as a feeling of identification with others using the familiar metaphor "walking in another's shoes," derived from the liberal-humanist therapeutic paradigm of Carl Rogers and Abraham Maslow, which assumes a universal and transparent human experience. The purpose of this study is to develop a theoretical framework for empathy, answering the question: what is the function of empathy in the teaching of writing? Composition scholarship has shown three general orientations toward empathy: empathy embraced, empathy inferred, and empathy disdained. In response, I trace empathy's development across disciplines as an aesthetic, ethical, physiological, and psychological construct using current research that shows empathy is a multifaceted, complex, cognitive process. In psychology and neuroscience, empathy is on the cutting edge of research, visible as brain activity in fMRI studies, theorized to have a vital role in evolution, and studied for its efficacy as a vehicle for altruistic action on behalf of stigmatized individuals and groups. Building on this multidisciplinary foundation, I offer an updated definition of empathy that invokes these scientific discoveries in order to account for empathy's role in the teaching and study of writing and rhetoric. I theorize there are five empathies at work in composition--relational empathy, pedagogical empathy, critical empathy, rhetorical empathy, and discursive empathy. I describe these empathies using another metaphor, that of a watershed, to illustrate empathy as part of a natural process whereby the five empathies are separate like the tributaries in a river system yet as inseparable as the water that fills them. Empathy's primary weaknesses, the familiarity and morality biases, are addressed; these are foundational to most criticisms of empathy. In the final chapter, I propose a sample course focusing on the study of rhetorical empathy, address the limitations of the study, provide many directions for further research, and argue that the study (and practice) of empathy itself and rhetorical empathy in particular are vital in today's uncertain times.