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
Ruy Pérez Ponce de León Ruy Pérez Ponce de León Ruy Pérez Ponce de León or Rodrigo Pérez Ponce de León (b. ? - d. 1295) was a Spanish noble of the House of Ponce de León, in the service of the Kingdom of Castile. He was the 15th Grand Master of the Order of Calatrava from 1284 to 1295 under King Sancho IV of Castile and further served as Mayordomo Mayor del Rey from 1293 - 1295, also under Sancho IV. Ruy was the son of the Count of Cabrera, Pedro Ponce de Cabrera and his wife, , one of the illegitimate daughters of