In architecture, Rationalism is an architectural current which mostly developed from Italy in the 1920s and 1930s. Vitruvius had claimed in his work De architectura that architecture is a science that can be comprehended rationally. This formulation was taken up and further developed in the architectural treatises of the Renaissance. Progressive art theory of the 18th-century opposed the Baroque use of illusionism with the classic beauty of truth and reason. The term Rationalism is commonly used to refer to the wider International Style.