Physiognomics is the theory according to which there is a relationship between certain signs on the body and certain characteristics of the soul, and furthermore that it is possible to exploit this relationship to transition from what is visible to what is invisible: to read the body in order to gain access to the soul. This Cambridge Element showcases the philosophical relevance of physiognomics during the Renaissance, combining in-depth analysis of physiognomics' subtle, and sometimes lesser-known theoretical details, with awareness of the role of physiognomics in the main philosophical debates of the time, including on the human-animal border and on the difference between men and women. This Element presents the Renaissance revival of physiognomics as a scientific endeavour that required philosophers to organise medical, anatomical, physiological, and astrological knowledge, under the aegis of an ethical programme for the improvement of oneself and society.