A sacrifice of material in order to achieve a superior pawn-structure is often a typical method for the side wishing to obtain a static advantage. Valeri Beim, Lessons In Chess Strategy
If one wants to decline the King's Gambit, 2...Bc5 has to be the most logical way, taking over the critical g1-a7 diagonal and preventing White from castling. John Watson, Mastering The Chess Openings - Volume 1
The club player often describes himself as having an 'attacking style' or a 'positional style'. When the sharp tactician falters in a quiet positional struggle, he blames it on 'not being my type of position'. If you think in this manner, you don't have a style, you have weaknesses. James Rizzitano, Understanding Your Chess
Players waste much more time and energy when they are forced to play a position that doesn't suit their style. David Navarra, The Secret Ingredient To Winning At Chess
This type of position (a symmetrical pawn-structure) has a psychological aspect. Its apparent harmlessness sometimes causes the opponent to relax prematurely, or, conversely, annoys the opponent and affects his judgment. Boris Zlotnik, Zlotnik's Middlegame Manual
In many instances two knights battle against two bishops better than do a bishop and knight, by occupying strong points created in the opening up of the position. Mikhail Shereshevsky, Endgame Strategy