There are roughly two opinions on this sentence.

(1) From the Bible. It is said that there was a king in ancient Arabia who had outstanding political achievements and made his people live happily. But as he grew older day by day, suddenly one day, he thought that everyone must die, and I should leave something for future generations...

So, he summoned nearly a hundred well-known people in the country Wise men, ask them to write a book together to summarize the eternal truth of the world. So these hundred wise men immediately began the work of compiling the book. They consulted ancient books and books, and went to the private sector to summarize and refine it. Finally, it took them three years to compile all the truths they collected and summarized into ten thick books. So, they happily took them to see the king...

But to their surprise, the king was not extremely happy, but only looked at the ten thick books on the table. Thick books, and told them, there are too many, please spend some more time selecting and compressing them before bringing them to me!

There was no other way. These hundred wise men had no choice but to go back and select and compress the ten books of truth that they had spent three years compiling. In this way, another two years passed quickly, and they finally compressed the ten books of truth into one, and took it to see their king with satisfaction. They thought, now there should be no problem!

However, the old king looked at the Book of Truth that they had worked so hard for five years to compile. He was still not satisfied with it and said, "Take it back again. This is still too much. I What we need is the only one, the classics!"

Now these wise men were "big-headed", but there was no other way. The king's words were orders, and they had to go back to their bookstores and continue to sort and sift. ...

In this way, another year passed... Finally, they found the answer and immediately came to the old king.

"Your Majesty the King, in accordance with your request, after a full 6 years, we finally found the eternal and only classic statement of truth that you wanted. It is - there is no such thing in the world. Free lunch!" The king smiled happily, and ordered the world to tell this simple and plain but profound truth to the whole country and educate the people...

(2) This sentence comes from the writings of political scientist Duran. In a paper published in 1971, he proposed two major principles. The first is "There is no free lunch principle in the world"; the second is "There is no impeccable influence principle in the world."

Regarding the connotation of this wise saying, it is that benevolence sees benevolence, and the wise see wisdom. But in general, it should be that it is impossible to get something for nothing at any time and anything.