Today is Halloween, and many children would have a good time. Nevertheless, happiness is not free, and it usually needs something to exchange for. Normally, their parents take the cost of happiness of having a good time on Halloween. Parents buy properties for their children and help them put on makeup, and finally they also have to cleanse their children of the makeup on the face. It is the cost of happiness of having a good time on Halloween. Many parents are really glad to take the cost to make their children have a good time on Halloween. However, I think it is better to let children take the cost of happiness themselves. If children always take the cost of happiness themselves, they would comprehend happiness is not a right they are born to have after they grow up. We live in a society of reality, and we have to pay something for happiness. The most important of all, paying is not guaranteed to enjoy happiness. Sometimes, we pay a lot, but we do not get happiness. The investment on the stock is a good example. After all, we live in a society of reality, not in a castle of fairy tales.