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
Libro de la invencion liberal y arte del juego del axedrez the second part, López introduces the word "gambit" and gives some openings that had not been previously published: the King's Gambit, some variations of the Bishop's Opening, and what is now known as the Steinitz Defense in the Ruy Lopez. The last two parts of the book are critical of the games of Damiano. After the moves 1.e4 e5 2.Nf3, Damiano thought that 2...Nc6 was Black's best move. López considered that inferior because of 3.Bb5. This opening is now known as the Ruy Lopez, although he did not invent it . Libro de la invencion liberal y arte del juego