The encyclical letter Laudato Si is available here on the Vatican website.
239. For Christians, believing in one God who is trinitarian communion suggests that the Trinity has left its mark on all creation. Saint Bonaventure went so far as to say that human beings, before sin, were able to see how each creature “testifies that God is three”. The reflection of the Trinity was there to be recognized in nature “when that book was open to man and our eyes had not yet become darkened”.[Quaest. Disp. de Myst. Trinitatis, 1, 2 concl.] The Franciscan saint teaches us that each creature bears in itself a specifically Trinitarian structure, so real that it could be readily contemplated if only the human gaze were not so partial, dark and fragile. In this way, he points out to us the challenge of trying to read reality in a Trinitarian key.
Bonaventure is one of our doctors. I had never been exposed to this notion before, that the human fall has clouded our sight from seeing more deeply this reality of God. Seeing does not equate to a full understanding, however.