"A tree gives glory to God by being a tree. For in being what God means it to be it is obeying him. It "consents," so to speak, to his creative love. It is expressing an idea which is in God and which is not distinct from the essence of God, and therefore a tree imitates God by being a tree.
The more a tree is like itself, the more it is like him. If it tried to be like something else which it was never intended to be, it would be less like God and therefore it would give him less glory.
For me to be a saint means to be myself. Therefore the problem of sanctity and salvation is in fact the problem of finding out who I am and of discovering my true self. Trees and animals have no problem. God makes them what they are without consulting them, and they are perfectly satisfied. With us it is different. God leaves us free to be whatever we like. We can be ourselves or not, as we please."