Is theoretical knowledge important to one's career achievement? By learning theories, students will be able to know the principles and concepts of different subjects, thus gradually becoming specialists of the fields. For example, psychiatrists cannot ensure the efficient therapy plans unless they know the sufficient theories that explaining the psychological diseases. Besides that, many theories have been developed on the basis of empirical knowledge, which is of practical meaning. People who master these theories are likely to have a good prospect and even obtain a great amount of fortune because of some innovations they did. Another benefit of theory learning is that it can improve people's problem-solving ability and their creativity. Theoretical knowledge can broaden student's mind and develop their critical thinking skills, which plays a key role in promoting the growth of knowledge in different theories themselves. In contrast, people who have never studied in university, admittedly, can attend practical trainings to tackle some ordinary problems, however, they may feel helpless when they are confronted with some irregular difficulties.