only to survive fully, and is for this reason regarded as 'the' zand. With the notable exception of the Yashts, almost all surviving Avestan texts have their Middle Persian zand, which in some manuscripts appear alongside (or interleaved with) the text being glossed. These glosses and commentaries were not intended for use as theological texts by themselves but for religious instruction of the (by then) non-Avestan-speaking public. In contrast, the Avestan language texts remained sacrosanct and continued to be recited in the Avestan language, which was considered a sacred language. Other exegetical works The corpus of medieval texts of Zoroastrian tradition include around 75 works, of which only a few are well known: the Denkard, "Acts of Religion", is an encyclopedic compendium of Sassanid era beliefs and customs. the Bundahishn, "Original Creation", is an important source of information on Zoroastrian cosmogony. Manushchihr's Dadestan i Denig ("Religious Decisions") and Epistles the Vichitakiha i Zatsparam, the "Treatises of Zatsparam", by Manushchihr's brother Zatsparam. the Arda-Viraf Namag relates the dream-journey of a devout Zoroastrian (the 'Viraf' of the story) through the next world. the Daedestan i Menog-i Khrad, "Judgments of the Spirit of Wisdom", is an andarz text (a class of Iranian wisdom literature) in which a figure named Danag (lit: "wise, knowing") participates in a question-and-answer dialog with Menog-i Khrad, the Spirit of Wisdom. the Jamasp Namag, "Book of Jamaspi", also known as the Ayadgar i Jamaspig "(In) Memoriam of Jamasp", is a compendium of essential doctrine, together with basic myth, legend, history, and some pseudo-prophetic matters cast as a series of revelations by Jamasp through the model of a question-and-answer dialog with Vishtasp. the Zand-i Wahman yasn is another pseudo-prophetic text, in this case cast as a question-and-answer dialog between Zoroaster and Ahura Mazda, in which the latter gives his prophet the ability to see into the future. the Shikand-gumanic Vichar, a partly apologetic and partly polemic review of other religions. the Shayast ne-shayast, "(on what is) Proper and Improper", a compilation of miscellaneous laws and customs regarding sin and impurity, with other memoranda about ceremonies and religious subjects in general. the Zaratosht-nama, an epic poem about the life of Zarathustra. Secular compositions A manuscript known as the "miscellaneous codex" or MK (after Mihraban Kaykhusrow, the Indian Zoroastrian (Parsi) copyist who created it), dated to 1322 but containing older material, is the only surviving source of several secular Middle Persian works