Saint Bonaventure took the spiritual intuition of Francis and made it into a theology. He taught that there are three books from which we learn wisdom: 1) The Book of Creation, 2) The Book of Jesus and Scripture, and 3) The Book of Experience. He also taught that there are three pairs of eyes. The first pair of eyes sees all things as a fingerprint or footprint of God (vestigia), which evokes foundational respect and teachability. The second pair of eyes are the hard work of honest self-knowledge--awareness of how you are processing your reality moment by moment. This is necessary to keep your own lens clean and open, and is the work of your entire lifetime. The third pair are the eyes of contemplation, which allow you to see things in their essence and in their core meaning. Only then can you receive the transmitted image of God on your soul. "Deep calls unto deep" as the Psalmist says (42:8), and all outer images can then mirror and evoke your own inner divine image. This is really quite brilliant and simple.
In his book, The Soul's Journey into God, Bonaventure says we must "begin at the bottom, presenting ourselves to the material world, seeing it as a mirror through which we may pass through to God, the Supreme Craftsman." He teaches that to really see things, we must "recognize in all material things their origin, their process, and their end." Everything comes from God, exemplifies God, and then returns to God. 
Ilia Delio, Keith Douglass Warner, and Pamela Wood explain how this Franciscan spirituality leads to caring for creation :
"The life of Francis shows us that to appreciate the book of creation we must come to know ourselves as creatures of God and as creatures of creation. Without self-knowledge, there can be no real knowledge of creation as our home and the womb of our birth. Without the human person to give voice to creation, to celebrate its giftedness and sacredness, creation becomes mute and vulnerable to manipulation.
"The key to creation's holiness, therefore, is in human identity--who we are in our Creator, the Trinity of divine love. This identity is revealed to us in Jesus Christ, the Word in whom we are made flesh. If God is alive in us, as [God] was in Francis, then we are alive to the world of God's good creation. However, if God is dead in us, then we are dead to the deeper meaning of creation as well.
"Francis realized that God humbly bends low in love and hides in simple, ordinary, fragile beings. So too we must realize that God is in our midst. Only when we can recognize creatures for what they are--expressions of God's overflowing love--can we recognize the source of our own lives as well. The love that gave birth to all creatures is the same love that has brought us into existence. This is what Francis realized, the luminous web of God's love revealed in Jesus Christ. We are called to live in this luminous web of love."