The origins of psychology as an independent discipline have long been a mystery. It has been unclear both when and on what basis psychology began to assert itself. Recently, there have been many individual attempts to uncover the details of this part of psychology’s history. This chapter is based on most of the recent findings in this area. Starting with Janssen and Hubbard’s landmark 2021 publication, where parts of humanist Pier Nicola Castellani’s manuscript from the 1520s have been made available in English, there are several signs that show how this term was both understood and used in the transition between the fifteenth and sixteenth centuries. With this as a starting point, this chapter explores where psychology comes from and how the content of this concept develops during the sixteenth century. The methodological approach in this work lies in viewing psychology in the light of the importance of the seven liberal arts (septem artes liberales). This was the package of preparatory subjects that all those in higher education in Europe had to acquire throughout virtually the entire Middle Ages. The core of the seven liberal arts lies in the clear distinction between the three philological sciences, namely grammar, dialectics, and rhetoric (trivium) on the one hand, and the four mathematical sciences, namely arithmetic, geometry, astronomy, and music (quadrivium) on the other. This chapter shows how perceptions of these sciences change throughout the sixteenth century and how the concept of psychology intertwines and blends with some of these disciplines. The main finding of this chapter is that the concept of psychology changes from being a very vague concept that is neither related to physics nor metaphysics, to having a fairly clear meaning at the end of the sixteenth century as it deals with our sensory nature. Since music also underwent the same change, references are also made to the close connection between the two disciplines of music and psychology during this period.