The Zohar: And though the essence of the heart of stone (Lev HaEven) cannot be corrected, its color nonetheless becomes corrected, for its black color is included in the three colors of holiness (bestowal) of the first nine Sefirot and receives luminescence and correction from them, This enables it to exist and be fit for being discerned in the future (at the End of Correction).
As I increase my desire to become similar to the Creator through my actions, by using my desire (Malchut) to be like bestowal, I sense the actions and qualities of the Creator in the first nine Sefirot of my soul. Meanwhile, I neutralize and cease using the desires belonging to Malchut (the heart of stone). As a result of this analysis and my effort to avoid working in the desires of Malchut (the heart of stone), Malchut becomes permeated by a tiny luminescence.
Later, once I become completely similar to the first nine Sefirot in my desire to bestow, by correcting my desires as much as possible and making them “for the sake of bestowal,” I discover that even the heart of stone can be used for the sake of bestowal. I find that it is precisely because I’ve always rejected and distanced it from myself and was unwilling to use it that it received an impression of bestowal. Thus it came to include within itself all the shades of the colors that I’d used in the first nine Sefirot.
There are only several colors – white, red, green and black, and I can use all of them except for black. Because I do not use the color black, the other colors allow it to include them within itself to a certain degree, and as a result it becomes fit for use. This is the meaning of the verse, “In the future the angel of death, egoism, shall become a holy angel, the quality of love and bestowal.” In other words, at the End of Correction the notion of “forbidden” will be revoked, as we’ll have the strength to use all of our desires for the sake of others.
Then all the restrictions and prohibitions will vanish in all axes of time, motion and space. This state is called the World of Infinity – a world without limits, where my existence is unbounded and I have unlimited opportunities.