  The capture of Constantinople by the Crusaders in 1204 dealt a severe blow to the Byzantine institutions of education and learning. Many teachers and scholars fled the city to find a haven in Nicaea, where the Laskarid dynasty had settled. Education and learning were matters of great concern to the Laskarid emperors; one of them, Theodore II Doukas Laskaris (ruled 1254–1258), was himself the author of two works on natural philosophy, Kosmikē dēlōsis (Cosmic Exposition) and Peri phusikēs koinōnias (On Physical Community), in which he brought simple mathematical schemes to bear on elemental theory and cosmology. In 1261 Constantinople was recaptured by Michael VIII Palaiologos, and the period of cultural prosperity that followed is sometimes referred to as the “Palaiologan renaissance”.