Mark Twain quotes are plentiful and used probably more than anyone else in American history. His broad range of life experiences, the people he met, invented and wrote about, the various jobs at which he worked and his uncanny knack for finding humor in most things offered Twain an expansion of life that few other authors possess. The following categorized quotes prove this point. Some of Mark Twain's most enduring quotations are about life, how it is best to live, and observations of how others live it; some are about what one should do to improve it. Here are some of the most widely known and a few obscure Mark Twain quotes about life:

• "Action speaks louder than words but not nearly as often."
• "Age is an issue of mind over matter. If you don't mind, it doesn't matter."
• "Let us live so that when we come to die even the undertaker will be sorry."
• "When your friends begin to flatter you on how young you look, it's a sure sign you're getting old."
• "Wrinkles should merely indicate where smiles have been."
• "Familiarity breeds contempt - and children."
• "I would rather have my ignorance than another man's knowledge, because I have so much more of it."- Letter to W.D. Howells, 1875
• "The best way to cheer yourself up is to try to cheer somebody else up."- Mark Twain's notebook
• "The man who is a pessimist before 48 knows too much; if he is an optimist after it, he knows too little."- Mark Twain's notebook, c. 1902-1903
• "Love seems the swiftest, but it is the slowest of all growths. No man or woman really knows what perfect love is until they have been married a quarter of a century." - Mark Twain's Notebook
• "Love is not a product of reasonings and statistics. It just comes--none knows whence--and cannot explain itself." - Eve's Diary
• "Love is a madness; if thwarted it develops fast."- "The Memorable Assassination"
• "The frankest and freest product of the human mind and heart is a love letter; the writer gets his limitless freedom of statement and expression from his sense that no stranger is going to see what he is writing"- Preface to Mark Twain's Autobiography, 1959
• "When you fish for love, bait with your heart, not your brain."- Notebook, 1898
• "Love is the irresistible desire to be irresistibly desired."
• "We write frankly and fearlessly but then we "modify" before we print."- Life on the Mississippi
• "Writing is easy. All you have to do is cross out the wrong words."
• "I notice that you use plain, simple language, short words and brief sentences. that is the way to write English — it is the modern way and the best way. Stick to it; don't let fluff and flowers and verbosity creep in." -letter to D.W. Bowser, 20 March 1880
• "The rules of literary art require that the author shall make the reader feel a deep interest in the personages of his take and in their fate; and that he shall make the reader love the good people in the tale and hate the bad ones."
• "The rules governing literary art require that the author shall say what he is proposing to say, not merely come near it."
• "I like the exact word, and clarity of statement, and here and there a touch of good grammar for picturesqueness." -The Autobiography of Mark Twain, 1924
• "An author values a compliment even when it comes from a source of doubtful competency." - Mark Twain in Eruption
• "That is just the way with some people. They get down on a thing when they don't know nothing about it."
• "Just because you're taught that something's right and everyone believes it's right, it don't make it right."
• "Human beings can be awful cruel to one another."
• "Hain't we got all the fools in town on our side? And hain't that a big enough majority in any town?"
• "You can't pray a lie -- I found that out."
• "What's the use you learning to do right, when it's troublesome to do right and it ain't no trouble to do wrong, and the wages is just the same?"
• "It is a time when one is filled with vague longings; when one dreams of flight to peaceful islands in the remote solitudes of the sea, or folds his hands and says, What is the use of struggling, and toiling and worrying anymore? Let us give it all up." - The Gilded Age
• "...no country can be well governed unless its citizens as a body keep religiously before their minds that they are the guardians of the law and that the law officers are only the machinery for its execution, nothing more."- The Gilded Age
• "Sometimes I wonder whether the world is being run by smart people who are putting us on or by imbeciles who really mean it."
• "Never argue with stupid people. They will drag you down to their level and then beat you with experience."
• "A lie can travel half way around the world while the truth is putting on its shoes."
• "If you don't read the newspaper, you're uninformed. If you read the newspaper, you're mis-informed."