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. We are at liberty to be real, or to be unreal. We may be true or false, the choice is ours. We may wear now one mask and now another, and never, if we desire, appear with our own true face. But we cannot make these choices with impunity. Causes have effects, and if we lie to ourselves and to others, then we cannot expect to find truth and reality whenever we happen to want them. If we choose the way of falsity we must not be surprised that truth eludes us when we finally come to need it!