primary script of the Persian language and the Turkish language. This script also heavily influenced the development of the cursive scripts of Greek, the Slavic languages, Latin, and other languages. The Arabic language also served to spread the Hindu–Arabic numeral system throughout Europe. By the beginning of the second millennium, the city of Córdoba in modern Spain had become one of the foremost intellectual centers of the world and contained the world's largest library at the time. Its position as a crossroads between the Islamic and Western Christian worlds helped fuel intellectual development and written communication between both cultures. Renaissance and the modern era By the 14th century a rebirth, or renaissance, had emerged in Western Europe, leading to a temporary revival of the importance of Greek, and a slow revival of Latin as a significant literary language. A similar though smaller emergence occurred in Eastern Europe, especially in Russia. At the same time Arabic and Persian began a slow decline in importance as the Islamic Golden Age ended. The revival of literacy development in Western Europe led to many innovations in the Latin alphabet and the diversification of the alphabet to codify the phonologies of the various languages. The nature of writing has been constantly evolving, particularly due to the development of new technologies over the centuries. The pen, the printing press, the computer and the mobile phone are all technological developments which have altered what is written, and the medium through which the written word is produced. Particularly with the advent of digital technologies, namely the computer and the mobile phone, characters can be formed by the press of a button, rather than making a physical motion with the hand. Writing materials There is no very definite statement as to the material which was in most common use for the purposes of writing at the start of the early writing systems. In all ages it has been customary to engrave on stone or metal, or other durable material, with the view of securing the permanency of the record. Metals, such as stamped coins, are mentioned as a material of writing; they include lead, brass, and gold. There are also references to the engraving of gems, such as with seals or signets. The common materials of writing were the tablet and the roll, the former probably having a Chaldean origin, the latter an Egyptian. The tablets of the Chaldeans