Question: Why can’t we correct the stony heart?
Answer: It is impossible to correct the stony heart since it is the gap between existence from existence and existence from absence. I can only resemble the Creator. To resemble means to form above me all the forms of the Creator that I see. Then the desire to receive takes on different forms of bestowal. This means that I can resemble Him like an actor, but I cannot resemble Him in all of my internality.
Only by all my corrections when all the Lights that I draw come together, will they operate the system and it will influence me by the Light that corrects the stony heart. I generate this process indirectly.
From the 2nd part of the Daily Kabbalah Lesson 8/04/13,The Book of Zohar — Introduction