Human Nature

There is a rotten apple in every barrel.
Birds of a feather flock together.
    Related proverb: You’re known by the company you keep.
Once bitten, twice shy.
If you want something done, ask a busy person.
When the cat’s away, the mice will play.
People expose their character in small actions. (Prolman)
You’re known by the company you keep.
    Related proverb: Birds of a feather flock together.
Throw enough dirt, and some will stick.
A drowning man will clutch at a straw.
The eyes are the window of the soul.
The grass is always greener on the other side of the fence.
Old habits die hard.
You can lead a horse to water, but you can’t make him drink.
Laugh and the world laughs with you; weep and you weep alone.
The leopard cannot change his spots.
Misery loves company.
Tall oaks from little acorns grow.
You can’t please everyone.
Power corrupts.
Give a man rope enough and he will hang himself.
Speech is silver, silence is golden.
The squeaky wheel gets the grease.
Today is the tomorrow that you worried about yesterday.
Travel broadens the mind.
Variety is the spice of life.
Virtue is its own reward.
Walls have ears.
All work and no play make Jack a dull boy.

You can’t see the fly on your own nose.

Boiling Frog (If you raise the temperature quickly, the frog jumps out of the pot;
    however, if you raise the temperature slowly, the frog doesn’t notice, and boils to death.)
Seeing a glass as half full or half empty.
Self-fulfilling prophecy
Wolf in sheep’s clothing.