Vitruvius was a Roman writer, architect, and engineer active in the 1st century BC. He was the most prominent architectural theorist in the Roman Empire known today, having written "De architectura" (known today as "The Ten Books of Architecture"), a treatise written in Latin and Greek on architecture, dedicated to the emperor Augustus. Probably written between 27 and 23 BC, it is the only major contemporary source on classical architecture to have survived. Divided into ten sections or "books", it covers almost every aspect of Roman architecture, from town planning, materials, decorations, temples, water supplies, etc. It rigorously defines the classical orders of architecture. It also proposes the three fundamental laws that architecture must obey, in order to be so considered: "firmitas, utilitas, venustas", translated in the 17th century by Sir Henry Wotton into the English slogan "firmness, commodity and delight" (meaning structural adequacy, functional adequacy, and beauty).