From Rod Kobayashi Shodo-o-seisu Seidokan Headquarters, 1986
The principle of shodo-o-seisu helps one have a deeper understanding of O'Sensei's teaching of masakatsu agatsu or "true victory is victory over oneself." If you calmly maintain control over yourself, you will not only find a way to control the opponent but will also be able to control the situation before drastic action is necessary. There will be no need to consider winning or losing, since there will be no contest. Both sides will be winners — the would-be attacker who didn't need to attack and the would-be defender who didn't need to defend.
From the web enumeration of Seidokan Aikido Principles by Rod Kobayashi
One must first learn to control oneself before attempting to harmonize and control others. Without a good balance and control of oneself, one can neither avoid an attack nor apply an effective technique on others. It is through self-control that one can learn to enjoy a harmonious way of life.