 In 1966 he published his second work, ""Commentary on the Book of the Kings of Truth" (Ḥaqq al-ḥaqāyiq yā Shāhnāmah-ʾi ḥaqīqat)," a commentary on his father's epic poem that expounded upon the determination of places and dates, the historical accuracy of certain events cited therein, and the concept of "divine manifestation".His third and final published work, a philosophical treatise titled ""Knowing the Spirit" (Maʻrifat al-rūḥ)," was published in 1969 and describes his ideas on the existence and immortality of the soul, and on the soul's gradual process of maturation and perfection.For Elahi, music was primarily a means of engaging in contemplation and prayer.