book, The Expression of Emotions in humans and animals (1872). It contained only a description of external manifestations, but it was a systemization, and thus the beginning of a scientific study of the subject.

An Italian psychologist Cesare Lombroso (1835-1909) was a criminologist who attempted to formally classify criminals based on age, gender, physical characteristics, education, and geographic region. When comparing these similar characteristics, he better understood the origin of motivation