Trivium
Etymologically, the Latin word trivium means "the place where three roads meet" (tri + via); hence, the subjects of the trivium are the foundation for the quadrivium, the upper division of the medieval education in the liberal arts, which consists of arithmetic (numbers as abstract concepts), geometry (numbers in space), music (numbers in time), and astronomy (numbers in space and time).
Educationally, the trivium and the quadrivium imparted to the student the seven liberal arts of classical antiquity.
Allegory of Grammar. Priscian on the left teaches Latin grammar to his students on the right. Relief by Luca della Robbia. Florence, Museo dell'Opera del Duomo.