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
Roderigo Lopez Roderigo Lopez Roderigo Lopez (also called Ruy Lopes, Ruy Lopez or Roger Lopez; c. 1517 – 7 June 1594) served as physician-in-chief to Queen Elizabeth I of England from 1581 until his death by execution, having been found guilty of plotting to poison her. A Portuguese "converso" or New Christian of Jewish ancestry, he is the only royal doctor in English history to have been executed, and may have inspired the character of Shylock in Shakespeare's "The Merchant of Venice", which was written within four years of his death. The son of a Portuguese royal physician of Jewish descent, Lopez