This article argues for the need to broaden the scholarly focus on the history of the modern discipline of psychology to include the history of psychological knowledge. It seeks to demonstrate the benefits to be derived from this endeavor by focusing on late antique psychology and presenting the novel methods of psychological investigation that emerged within the Christian monastic movement, especially introspection. Far from being a historically recent invention, I argue that introspection was systematically and self-consciously employed by late antique monks as a method for producing knowledge about the human mind. Yet rather than arguing for a simple continuity between late antique and modern introspective procedures, a comparison between early monastic introspective accounts and those of the founders of the modern psychology reveals profound differences in the interpretation and evaluation of introspective data; thereby, it allows one to address fundamental questions related to the nature of psychological knowledge and its relationship with culturally constructed categories. (PsycINFO Database Record (c) 2019 APA, all rights reserved)