Giving up the center must not here be regarded as illogical. Was happiness no happiness because it endured for just a short time? One cannot always be happy.
Aron NimzowitschThe knight of QB3 is under obligation, the moment the enemy gives him the chance, of undertaking an invasion of the center by Kn-Q5.
Aron NimzowitschThe main Objective of any operation in an open file is the eventual Occupation of the seventh or eighth Rank.
Aron NimzowitschIt is a well known phenomenon that the same amateur who can conduct the middle game quite creditably, is usually perfectly helpless in the end game. One of the principal requisites of good chess is the ability to treat both the middle and end game equally well.
Aron Nimzowitsch