51 By this Encyclical Letter We are instituting a feast so that all may recognize more clearly and venerate more devoutly the merciful and maternal sway of the Mother of God. We are convinced that this feast will help to preserve, strengthen and prolong that peace among nations which daily is almost destroyed by recurring crises. Is she not a rainbow in the clouds reaching towards God, the pledge of a covenant of peace? "Look upon the rainbow, and bless Him that made it; surely it is beautiful in its brightness. It encompasses the heaven about with the circle of its glory, the hands of the Most High have displayed it." Whoever, therefore, reverences the Queen of heaven and earth - and let no one consider himself exempt from this tribute of a grateful and loving soul - let him invoke the most effective of Queens, the Mediatrix of peace; let him respect and preserve peace, which is not wickedness unpunished nor freedom without restraint, but a well-ordered harmony under the rule of the will of God; to its safeguarding and growth the gentle urgings and commands of the Virgin Mary impel us.
Source: Ad Caeli Reginam (Vatican.va)