The dissertation surveys the historical development and meanings of the term milieu, tracing its origins in physical usage and its expansion into biological and social contexts. It examines linguistic equivalents and translations, summarizes debates over inner and outer milieu, and reviews anthropogeographical literature linking climate, terrain, and human societies. Sections consider how physical environment has been argued to affect social organization, religion, intellect, conduct, diet, and political phenomena. Compiled as a preliminary, source-rich sketch rather than an empirical treatise, it aims to map the theory's evolution and to prepare subsequent analysis of specific thinkers' conceptions.