To have a complete knowledge of a person one must know if he does right why he does right, and if he does wrong why he does wrong, if he is wise what makes him wise, if he is foolish what is the reason of his being foolish; not only this, but also if there were a possibility of making the best of what the person is and trying to improve the person without him knowing it. A foolish person cannot get along with his own friend whereas a wise person can get on even with his enemy. The difference is that the one knows life, understands human nature and acts according to it, whereas the other, even if he wanted to act rightly, always fails and becomes disappointed in the end.