In the early Gothic, the facades were characterized by height, elegance, harmony, unity, and a balance of proportions. They followed the doctrine expressed by Saint Thomas Aquinas that beauty was a "harmony of contrasts." Following the model of Saint-Denis and later Notre-Dame de Paris, the facade was flanked by two towers proportional to the rest of the facade, which balanced the horizontal and vertical elements. Early Gothic facades often had a small rose window placed above the central portal. In England the rose window was often replaced by several lancet windows.