In his comprehensive main work "Outlines of a Philosophy of Technology" (1877), the educator, geographer, and philosopher Ernst Kapp undertakes the far-reaching attempt to understand all technical artifacts as an "organ projection" of the human body. This means that humans unconsciously transfer the form, functional relationships, and normal proportions of their bodily structure onto the works of their hands, and they only become aware of these analogous relationships to themselves afterward. Kapp thus derives the invention of technical things from the model of the human organism, but especially from the human hand, which serves as a natural tool that determines the form and purpose of all mechanical tools. The prevailing Cartesian metaphor of the organic as merely mechanical up to the 19th century is therefore almost inverted in Kapp's work.