In medieval universities, the trivium comprised the three subjects that were taught first: grammar, logic, and rhetoric. The word is a Latin term meaning "the three ways" or "the three roads" forming the foundation of a medieval liberal arts education. This study was preparatory for the quadrivium, which consists of geometry, arithmetic, astronomy, and music. Combining the trivium and quadrivium results in the seven liberal arts of classical study. The trivium is implicit in the De nuptiis of Martianus Capella, although the term was not used until the Carolingian era when it was coined in imitation of the earlier quadrivium. It was later systematized in part by Petrus Ramus as an essential part of Ramism. Logic, grammar, and rhetoric were very important for a classical education, as clearly explained in Plato's dialogues. The three together were defined into one word in the Middle Ages, but the tradition of learning these three first was well established in Plato's time, or even earlier.