I do not want to write this encyclical without turning to that attractive and compelling figure, whose name I took as my guide and inspiration when I was elected Bishop of Rome. I believe that Saint Francis is the example par excellence of care for the vulnerable and of an integral ecology lived out joyfully and authentically. [My emphasis here and below. —RR]He is the patron saint of all who study and work in the area of ecology, and he is also much loved by non-Christians. He was particularly concerned for God’s creation and for the poor and outcast. He loved, and was deeply loved for his joy, his generous self-giving, his openheartedness. He was a mystic and a pilgrim who lived in simplicity and in wonderful harmony with God, with others, with nature, and with himself. He shows us just how inseparable the bond is between concern for nature, justice for the poor, commitment to society, and interior peace.
. . . [Francis’] response to the world around him was so much more than intellectual appreciation or economic calculus, for to him each and every creature was a sister [or brother] united to him by bonds of affection. This is why he felt called to care for all that exists. His disciple Saint Bonaventure tells us that, “from a reflection on the primary source of all things, filled with even more abundant piety, he would call creatures, no matter how small, by the name of ‘brother’ or ‘sister.’”  Such a conviction cannot be written off as naïve romanticism, for it affects the choices which determine our behavior. If we approach nature and the environment without this openness to awe and wonder, if we no longer speak the language of fraternity and beauty in our relationship with the world, our attitude will be that of masters, consumers, ruthless exploiters, unable to set limits on their immediate needs. By contrast, if we feel intimately united with all that exists, then sobriety and care will well up spontaneously. The poverty and austerity of Saint Francis were no mere veneer of asceticism, but something much more radical: a refusal to turn reality into an object simply to be used and controlled.
What is more, Saint Francis, faithful to Scripture, invites us to see nature as a magnificent book in which God speaks to us and grants us a glimpse of his infinite beauty and goodness. “Through the greatness and the beauty of creatures one comes to know by analogy their maker” (Wisdom 13:5); indeed, “his eternal power and divinity have been made known through his works since the creation of the world” (Romans 1:20).