Despite this ambiguity, monasteries in the West and the Eastern Empire permitted the conservation of a certain number of secular texts, and several libraries were created: for example, Cassiodorus ('Vivarum' in Calabria, around 550), or Constantine I in Constantinople. There were several libraries, but the survival of books often depended on political battles and ideologies, which sometimes entailed massive destruction of books or difficulties in production (for example, the distribution of books during the Iconoclasm between 730 and 842). A long list of very old and surviving libraries that now form part of the Vatican Archives can be found in the Catholic Encyclopedia.