Most chess players know, thanks to the study of master games, that two bishops are stronger than two knights or than bishop and knight, though very few know the reason for this advantage and how to turn it to account.
Richard RetiThe essential disadvantage of the isolated pawn ... lies not in the pawn itself, but in the square in front of the pawn.
Richard RetiA knowledge of tactics is the foundation of positional play. This is a rule which has stood its test in chess history and one which we cannot impress forcibly enough upon the young chess player. A beginner should avoid Queen's Gambit and French Defence and play open games instead! While he may not win as many games at first, he will in the long run be amply compensated by acquiring a thorough knowledge of the game
Richard RetiThe majority of people imagine a chess master as being a townsman who passes his life in an atmosphere of smoke and play in cafes and clubs: a neurasthenic individual, whose nerves and brains are continually working at tension: a one-sided person who has given up his whole soul to chess.
Richard Reti