Chess opening are so complex and theoretical that amateur players will have trouble understanding them. An example is the Perenyi Attack of the Sicilian Defense (see diagram) which yields an immensely complicated and tactical position that even strong players have difficulty handling, and that is beyond the comprehension of most amateurs. Major changes in the rules of chess in the late fifteenth century increased the speed of the game, consequently emphasizing the importance of opening study. Thus, early chess books, such as the 1497 text of Luis Ramirez de Lucena, present opening analysis, as does Pedro Damiano (1512), and Ruy López de
Sicilian language either side) and had a significant influence on the Sicilian vocabulary. The following words are of Spanish derivation: Since the Italian Unification (the Risorgimento of 1860–1861), the Sicilian language has been significantly influenced by (Tuscan) Italian. During the Fascist period it became obligatory that Italian be taught and spoken in all schools, whereas up to that point, Sicilian had been used extensively in schools. This process has quickened since World War II due to improving educational standards and the impact of mass media, such that increasingly, even within the family home, Sicilian is not necessarily the language of choice. The