The Law of Reciprocity

Do unto others as you would have others do unto you.

Do to others as you would have them do to you.

To give and take mutually.

To return in kind or even in another kind or degree.

I'll scratch your back if you scratch mine.

You reap what you sow.

Whoever sows sparingly will also reap sparingly, and whoever sows generously will also reap generously.... And God is able to make all grace abound to you, so that in all things at all times, having all that you need, you will abound in every good work.

For every action, something is expected in return.

For every action, there is an equal and opposite reaction.

Smile at another person, and he'll probably smile back at you.

Be critical of others, and they'll respond in kind.

As you give, you will receive.

Give generously, and you'll receive in like measure