The phrase "heaven of heaven" is often used in religious texts to describe the highest level of heaven. However, there are several synonyms that can be used to describe this concept. One such synonym is "paradise," which is often used to describe a place of ultimate happiness and bliss. Another synonym is "eternal kingdom," which suggests a realm that is infinite and everlasting. "Elysium" is yet another synonym, borrowed from Greek mythology, which refers to a place of perfect happiness and serenity. Whatever the term used, the idea of a "heaven of heaven" represents the ultimate goal for many believers, and a place of perfect peace and joy.