Why did Galileo Galilei leave the University of Pisa without a degree?

Galileo Galilei left the University of Pisa in 1585 without a degree because his academic interests shifted significantly during his studies. Although he originally matriculated in 1581 to study medicine, he became deeply enamoured with mathematics.

He ultimately decided to pursue mathematical subjects and philosophy as his profession, a choice he made against the wishes of his father. Following his departure from the university, he spent several years providing private lessons in mathematics in Florence and Siena before eventually securing a teaching position at the university level later in his career.1