'Give all that you can but expect none from the others' is the slogan that people advise the disturbed souls. For the universe to be balanced, they say that for every particle there is an anti-particle. So if one person is giving away something to the other, definitely there shall be an imbalance because the giver receives nothing as per the general perception. However, the world doesn't survive if there is such an imbalance. Hence we jump into the theory of, 'for every something that is given there is always something taken as well'.
Let's take a few examples and prove this hypothetical theory. If someone gives another person some amount of money then he receives back a promise that he shall repay the amount. May be the give and take doesn't happen in equivalent form of an object but definitely in equivalent forms of feelings. The guy receiving the money is happy and the guy lending the money is happy because he knows that he will get back his money with extra interest added to it. In a class, when a teacher is teaching, she is passing on her knowledge to the students in exchange for their attention. The teacher gets attention for her teaching while the students get education for their attention. In above two examples, if the receiver would be absent i.e., either the students or the loan receiver then there would be no scope for the lender or the teacher to exist to perform their roles just like how if all planets cease to exist, the sun would have no reason to burn. So there is always a trade of something for something in this universe.
If we accept the theory of this barter that there is always that's got for something that's lost or given away, a lot of problems and worries in our life can be reduced. If a thief steals away your money, it only means that he gave back the lesson of safety to you. If a friend cheated your trust, he only gave back an experience to trust a friend carefully in future. In every possible situation, your assets remain the same. Only that, with every occurring transaction the form of your assets keeps changing. When you know that you receive something for every something that you lend out, then why worry? You can just be happy always. You can throw in your comments here.