In chess, there is only one mistake: over-estimation of your opponent. All else is either bad luck or weakness.
To avoid losing a piece, many a person has lost the game
I talk to myself because I like dealing with a better class of people.
It's always better to sacrifice your opponent's men
It is well-known that chess and music go well together, and many are those who have achieved unusual proficiency in both.
No one ever won a game by resigning.