Life is very important to be understood so we need knowledge to understand it. We know that there are two types of knowledge; the first one is gained from books and the other one is gained from experience. Some people believe that everything that is learned is contained in books and others don't believe that. The first one is called theoretical knowledge and the other is practical knowledge. In my opinion practical knowledge is more important than theoretical knowledge. There are reasons for this point of view and I'll summarize them.