Physiognomy is the art or science of ascertaining the character of the mind of an individual by studying the features of his body especially face. So it is an art of judging or discovering temperament or character from outward appearance.
A man generally thinks according to his formation, and not only does he think according to his formation, but he acts and works in accordance therewith. External appearance and the internal environment vary from person to person. That is where physiognomy has its role to play.