Returning a gambit pawn by way of pushing it is not to be recommended in any gambit variation, because it does not aid development. András Mészáros, Traps In The Opening
Passive play against the Minority Attack is usually fatal. The best defence is counterattack on the kingside. Steve Giddins, 50 Essential Chess Lessons
If you seize a large hunk of the centre in the first moves of the game, make sure that you can defend the pawns that control that territory. John Watson, Mastering The Chess Openings - Volume 1
The ideal which lies at the root of every operation in a file is the ultimate penetration by way of this file into the enemy's game, that is to say to our own seventh or eighth rank. Aron Nimzowitsch, My System - 21st Century Edition
The general objective every chessplayer should have during the game is to secure a harmonious cooperation between his pieces and pawns. Alexey Sokolsky, The Modern Openings In Theory And Practice
When there is a structural imbalance, opposite-coloured bishops tend to favour the attacker because the defender is often powerless to prevent the infiltration of his position. James Rizzitano, Understanding Your Chess