Ambrose Bierce

Cogito cogito ergo cogito sum -- "I think that I think, therefore I think that I am."

 Ambrose Bierce, in  Wisdom and Ignorance

Coward: one who, in a perilous emergency, thinks with his legs.

 Ambrose Bierce, in  Vice and Virtue and  War and Peace

Diplomacy: The patriotic art of lying for one's country.

 Ambrose Bierce, The Devil's Dictionary, in  Law and Politics

Helpmate: A wife, or bitter half.

 Ambrose Bierce, The Devil's Dictionary, in  Love and Hate

In Dr. Johnson's famous dictionary, "patriotism" is defined as the last resort of the scoundrel. With all due respect to an enlightened but inferior lexicographer, I beg to submit that it is the first.

 Ambrose Bierce, in  Law and Politics

Incompatibility: In matrimony a similarity of tastes, particularly the taste for domination.

 Ambrose Bierce, The Devil's Dictionary, in  Love and Hate

It has been observed that one's nose is never so happy as when it is thrust into the affairs of another, from which some physiologists have drawn the inference that the nose is devoid of the sense of smell.

 Ambrose Bierce, in  Vice and Virtue

Knowledge is the small part of ignorance that we arrange and classify.

 Ambrose Bierce, in  Wisdom and Ignorance

The covers of this book are too far apart.

 Ambrose Bierce, in  Altruism and Cynicism