The rule of casting out all negative thoughts, and keeping them out, is an absolute one. There are no exceptions and no deviations. Such negatives as hate, irritability, and fault-finding make poisons in the body and neuroses in the mind. They irritate the nerves, disturb the proper movement of the blood, distort the internal secretions, and destructively affect the chemical composition of tissue cells. Nor is this the end. They provoke like emotions in other people with whom we are constantly thrown in contact. We then have to suffer the effects as if they were echoes of our own making. Thus the discords inside oneself throw up disturbances outside oneself. One's anger provokes the other person's anger, for instance.
-- Notebooks Category 11: The Negatives > Chapter 5: Their Visible and Invisible Harm > # 64