Most of our so-called reasoning consists in finding arguments for going on believing as we already do.
James Harvey Robinson (The Mind in the Making)

Blessed are they who have nothing to say and who cannot be persuaded to say it.
James Russell Lowell

You cannot get ahead while you are getting even.
Rep. Dick Armey

If it's stupid, but it works, it's not stupid.

Better to light a candle than to curse the darkness.
Chinese proverb

That you may retain your self-respect, it is better to displease the people by doing what you know is right, than to temporarily please them by doing what you know is wrong.
William J.H. Boetcker

The books that the world calls immoral are the books that show the world its own shame.
Oscar Wilde

In the beginner's mind there are many possibilities, but in the expert's mind there are few.
Shunryu Suzuki

Do not believe in anything simply because you have heard it. Do not believe in anything simply because it is spoken and rumored by many. Do not believe in anything simply because it is found written in your religious books. Do not believe in anything merely on the authority of your teachers and elders. Do not believe in traditions because they have been handed down for many generations. But after observation and analysis, when you find that anything agrees with reason and is conducive to the good and benefit of one and all, then accept it and live up to it.
Buddha

I have learned throughout my life as a composer chiefly through my mistakes and pursuits of false assumptions, not by my exposure to founts of wisdom and knowledge.
Igor Stravinsky

Reputation is in itself only a farthing candle, of a wavering and uncertain flame, and easily blown out, but it is the light by which the world looks for and finds merit.
James Russell Lowell

Nothing in life is to be feared. It is only to be understood.
Marie Curie

Life is like music; it must be composed by ear, feeling, and instinct, not by rule.
Samuel Butler

One sign of maturity is the ability to be comfortable with people who are not like us.
Virgil A. Kraft

You probably wouldn't worry about what people think of you if you could know how seldom they do.
Olin Miller

Education would be much more effective if its purpose was to ensure that by the time they leave school every boy and girl should know how much they do not know, and be imbued with a lifelong desire to know it.
Sir William Haley

Happiness is not having what you want. It's wanting what you have.

Life is made up of small pleasures. Happiness is made up of those tiny successes. The big ones come too infrequently. And if you don't collect all these tiny successes, the big ones don't really mean anything.
Norman Lear

Most people would succeed in small things if they were not troubled with great ambitions.
Henry Wadsworth Longfellow

Try a thing you haven't done three times. Once, to get over the fear of doing it. Twice, to learn how to do it. And a third time, to figure out whether you like it or not.
Virgil Thomson (advice given at age 93)

When you blame others, you give up your power to change.
Dr. Robert Anthony

Dignity does not consist in possessing honors, but in deserving them.
Aristotle

Expedients are for the hour; principles for the ages.
Henry Ward Beecher

Nothing dries sooner than tears.

Many a man's tongue has broken his nose.

A tart temper never mellows with age; and a sharp tongue is the only edged tool that grows keener with constant use.

A wise man may look ridiculous in the company of fools.

known authors as stated
(hopefully these are all actually attributed to the correct authors)

.....