The function of science is to reassure; the purpose of art is to upset. Therein lies the value of each.
Science and art are two of the most glorious fields in which numerous people have made their great contributions. As the society develops, people concern more about the function of science, of art and of other realms. Some may argue that the function of science is to reassure, and the purpose of art is to upset, however, as far as I am concerned, science and art have more significant values than just to reassure or to upset people.
The main function of science is to propel the development of human society and to provide people the power to understand the nature and ourselves. In the primordial days of the human history, when the conception of science first emerged, science was to answer people's questions and to satisfy people's curiosity towards myriad mysterious phenomenon. If we understand the science in such way, we can't see clear differences between the inchoate religion and the inchoate science, because, the functions of both of them are nearly the same, and both contain totally absurd theories if one studies them today. One may agree that in that period of time, science was largely to reassure people's fear towards the mysteries just as what religions try to do.
However, the development of science finally makes it an important tool for us to understand the nature and to change the nature in our favor. The understanding of electricity expels the old thought that the thunder is a sign indicating that the god is angry. The advancement achieved in medicine greatly elongate human's life, and nowadays people no longer depend on certain rituals to give them health. Discoveries and inventions alike have transformed our society into the nowadays form, and provide us great power to determine our future. If science is only to reassure us, how can we achieve the feats we have made through our history? As Francis Bacon once said, "Knowledge is power", the true function of science is to give us the power to conquer the difficulties we confront.
Unlike science, arts which seldom give us the power to better our material lives, mainly concern about our spiritual lives. Admittedly, some arts actually upset people by let us see the weakness of the human nature or the darkness of our society, as the art works of Michelangelo. However, arts possess much more functions than just upset us. Arts can ease our emotions and reassure us, as the music of Mozart does; arts can give us confidence and braveness, as the music of Beethoven does; arts can also tell us what philosophy is, as the music of Mahler does. Although arts possess so many functions,one can judge that the major function of art is to represent the life and to present the artists' ideals. Most literary works, such as fictions, poems, dramas, give us a vivid image of the society. Other forms of arts have the same kind of functions. For example, Tchaikovsky composed music to represent the hard life of the common Russian people, while Van Gogh drew pictures to represent the beauty of the nature. There're also other pieces of art showing us the inner part of the artists, for instance, the representative new trend movie "four hundred blows". By presenting the life and the ideals, arts give us true understanding of our circumstances and ourselves in a spiritual way. Arts can not explain why it rains,but it explains how people feel about the rainy day.