Philosophers have been speculating on the rules of human relationships for thousands of years, and out of all that speculation, there has evolved only one important precept. It is not new. It is as old as history. Zoroaster taught it to his followers in Persia twenty five hundred years ago. Confucius preached it in China twenty-four centuries ago. Lao-tse, the founder of Taoism, taught it to his disciples in the Valley of the Han. Buddha preached it on the bank oft he Holy Ganges five hundred years before Christ. The sacred books of Hinduism taught it a thousand years before that. Jesus taught it among the stony hills of Judea nineteen centuries ago. Jesus summed it up in one thought – probably the most important rule in the world: “Do unto others as you would have others do unto you.”

— Dale Carnegie, “How to Win Friends & Influence People”