Quietude is a very positive state; there is a positive peace which is not the opposite of conflict—an active peace, contagious, powerful, which controls and calms, which puts everything in order, organises. It is of this I am speaking; when I tell someone, “Be calm”, I don’t mean to say “Go and sleep, be inert and passive, and don’t do anything”, far from it!… True quietude is a very great force, a very great strength. In fact one can say, looking at the problem from the other side, that all those who are really strong, powerful, are always very calm. It is only the weak who are agitated; as soon as one becomes truly strong, one is peaceful, calm, quiet, and one has the power of endurance to face the adverse waves which come rushing from outside in the hope of disturbing one. This true quietude is always a sign of force. Calmness belongs to the strong.
Ref: Questions And Answers 1956