By "luxury", we mean "a pleasant and often expensive thing that is not necessary". From a historical point of view, things which Were a luxury when they first came into being all became necessities later. When the electric bulb was first invented in the U.S., it was such a luxury that only government bodies could afford to use it. Nowadays, however, it has reached every part of the world. It is the same case with telephone, TV, and a lot of others, which were all luxuries years ago.
     Anything, no matter how luxurious it is, will become a necessity when it is widely used. This is true of many of the present luxuries, including mobile phones, cars, computers and many other things. It is known to all that the purpose of the development of science is to make things easy for the mankind, not for only a small number of people. Therefore, the first thing to do after a new invention occurs is to spread it so as to benefit as many people as possible. In the course of the spread, the luxury becomes decreasingly luxurious until in the end it becomes a necessity. This is an objective law, nothing can be an exception.
     With the quick development of science and technology, the process for many things to become a necessity from a luxury will be greatly shortened. Anything that can be imagined will be invented and in no time becomes a necessity accessible to ordinary people.