self-observation, a source of knowledge

The focus of science is on nature, on things outside ourselves, and scientists almost always gather information from external sources. As a student majored in science, I used to believe the external word is the only source of information. But gradually I realize another rich source of knowledge; it lies inside myself. Feelings, emotions, personal values, moral principles, and even interests can only obtained through searching within myself. It is the observation of me that gives me all the these knowledge. "Know thyself"!