Omar Khayyam's Secret: Hermeneutics of the Robaiyat in Quantum Sociological Imagination, by Mohammad H. Tamdgidi, is a 12-book series of which this book is the 7th volume, subtitled Khayyami Art: The Art of Poetic Secrecy for a Lasting Existence: Tracing the Robaiyat in Nowrooznameh, Isfahan's North Dome, and Other Poems of Omar Khayyam, and Solving the Riddle of His Robaiyat Attributability. Each book, independently readable, can be best understood as a part of the whole series. In Book 7, Tamdgidi shares his updated edition of Khayyam's Persian book Nowrooznameh, and for the first time his new English translation of it, followed by his analysis of its text. He then visits recent findings about the possible contribution of Khayyam to the design of Isfahan's North Dome. Next, he shares the texts, and his new Persian and English translations and analyses of Khayyam's other Arabic and Persian poems. Finally he studies the debates about the attributability of the Robaiyat to Khayyam. Tamdgidi verifiably shows that Nowrooznameh was written by Khayyam, arguing that its unjustifiable neglect has prevented Khayyami studies from answering important questions about Khayyam's life, works, and his times. Nowrooznameh is primarily a work in literary art, rather than in science, tasked not with reporting on past truths but with creating new truths in the spirit of Khayyam's conceptualist view of reality. Iran owes the continuity of its Zoroastrian calendar month names to the way Khayyam artfully recast their meanings in the book in order to prevent their being dismissed during the Islamic solar calendar reform underway under his invited direction. The book also sheds light on the mysterious function of Isfahan's North Dome, revealing it as having been to serve, as part of an observatory complex, for the annual Nowrooz celebrations and leap-year declarations of the new calendar. The North Dome, to whose design Khayyam contributed and in fact bears symbols of his unitary view of a world created for happiness by God, marks where the world's most accurate solar calendar of the time was calculated. It deserves to be named after Omar Khayyam (not Taj ol-Molk) and declared as a cultural world heritage site. Nowrooznameh is also a pioneer in the prince-guidance books genre that anticipated the likes of Machiavelli's The Prince by centuries, the difference being that Khayyam's purpose was to inculcate his Iranian and Islamic love for justice and the pursuit of happiness in the young successors of Soltan Malekshah. Iran is famed for its ways of converting its invaders into its own culture, and Nowrooznameh offers a textbook example for how it was done by Khayyam. Nowrooznameh also offers by way of its intricately multilayered meanings the mediating link between Khayyam's philosophical, theological, and scientific works, and his Robaiyat, showing through metaphorical clues of his beautiful prose how his poetry could bring lasting spiritual existence to its poet posthumously. Khayyam's other Arabic and Persian poems also provide significant clues about the origins, the nature, and the purpose of the Robaiyat as his lifelong project and magnum opus. Tamdgidi argues that the thesis of Khayyam's Robaiyat as a secretive artwork of quatrains organized in an intended reasoning order as a 'book of life' serving to bring about his lasting spiritual existence can solve the manifold puzzles contributing to the riddle of his Robaiyat attributability. He posits, and in the forthcoming books of this series will show, that the lost quatrains comprising the original Robaiyat have become extant over the centuries, such that we can now reconstruct, by way of solving their 1000-piece jigsaw puzzle, the collection as it was meant to be read as an ode of interrelated quatrains by Khayyam.