A long, long time ago, I was young. At that time, I was probably just like you, full of curiosity about the world, and constantly exploring forward. However, I only have this short life. The universe is so big, everything is so complex, and love is so deep, I have no time to find the entrance, so I will grow old. I just want to leave this long letter to time, to me in the past, and to all the young people.