Knowledge light our mind. It enables a man to have a master over all forces of nature. There are so many wild beasts which are strong than a man and light and earthquakes which can destroy man and his civil in a moment. But a man rules over them all accord to his wish. He makes use of the solar power to bright the night. He is the conquer of time and space. All discoveries and invent are the results of his know. It makes him doubt the mightiest of all the create in the universe. To maintain superior, man has to work through his life.