The European Renaissance evoked under kings Sigismund I the Old and Sigismund II Augustus a sense of urgency in the need to promote a cultural awakening. During this period Polish culture and the nation's economy flourished; changes and contributions to architecture, cuisine, language and customs were made at the behest of Sigismund the Old's wife, the Italian-born Bona Sforza, daughter of the Duke of Milan. In 1543, Nicolaus Copernicus, an astronomer from Toruń, published his epochal work ''De revolutionibus orbium coelestium'' (''On the Revolutions of the Celestial Spheres'') and thereby became the first proponent of a predictive mathematical model confirming the heliocentric theory, which became the accepted basic model for the practice of modern astronomy.