All Chess players should have a hobby
It is said that an ounce of common sense can outweigh a ton of 'variations'.
An isolated pawn spreads gloom all over the chessboard.
Lasker thought that his rationalism rendered him immune from the surprises of chess theory.
Psychologically, the choice of an appropriate opening is of the utmost importance for a player's success in a tournament.
Any opening is good enough, if its reputation is bad enough.