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
Four Knights Game attempt for White to exploit the advantage of the first move. In the 1990s, this opening saw a renaissance, and is now seen in the praxis of players from beginner to grandmaster. The Four Knights usually leads to quiet , though there are some variations. The "ECO" codes for the Four Knights Game are C49 (Symmetrical Variation, 4.Bb5 Bb4), C48 (4.Bb5 without 4...Bb4), C47 (4.d4 and others). White's most common move is 4.Bb5, the Spanish Variation. This variation can also be reached from the Ruy Lopez, Berlin Defence. After 4.Bb5, Black has three major alternatives. The first of these is