Outbursts of violent temper hinder the right development of the emotions and also the will, and also have a far more extensive influence, as we can see at once. Now, anger is something that a person does not by any means have under his control. Only gradually can he master the habit of becoming angry, and one must have patience with oneself.
To anyone who believes he can achieve this with a turn of the hand I must repeat the story of a teacher who took very much to heart the task of ridding his pupils of anger. When he was faced by the fact, that after constant efforts, a boy still became angry, he himself became so angry that he threw the ink bottle at the child’s head. A person who permits himself to do such a thing must think for many, many weeks about karma.
Source: Rudolf Steiner – GA 130 – Esoteric Christianity and the Mission of Christian Rosenkreutz – Lecture 2 – Leipzig, 5th November 1911