You may think this is ridiculous, I have been a teacher for 15 years, and all I knew about the world was the pictures of China, Asia, Africa and Europe, the bigger pictures still would be Earth, Moon and Mars, and extended to the galaxy. After course, I realized that the world refers to time and space. It was then that I felt how tiny I am, and how ridiculous it really is for human beings to think they know so much! Coming here was really rewarding.