The Dalá’il-i-Sab‘ih (Seven Proofs), the most important of the polemical works of the Báb, was revealed during that same period. Remarkably lucid, admirable in its precision, original in conception, unanswerable in its argument, this work, apart from the many and divers proofs of His mission which it adduces, is noteworthy for the blame it assigns to the “seven powerful sovereigns ruling the world” in His day, as well as for the manner in which it stresses the responsibilities, and censures the conduct, of the Christian divines of a former age who, had they recognized the truth of Muḥammad’s mission, He contends, would have been followed by the mass of their co-religionists. During the Báb’s confinement in the fortress of _Ch_ihríq, where He spent almost the whole of the two remaining years of His life, the Lawḥ-i-Hurúfat (Tablet of the Letters) was revealed, in honor of Dayyán—a Tablet which, however misconstrued at first as an exposition of the science of divination, was later recognized to have unravelled, on the one hand, the mystery of the Musta_gh_á_th_, and to have abstrusely alluded, on the other, to the nineteen years which must needs elapse between the Declaration of the Báb and that of Bahá’u’lláh. It was during these years—years darkened throughout by the rigors of the Báb’s captivity, by the severe indignities inflicted upon Him, and by the news of the disasters that overtook the heroes of Mázindarán and Nayríz—that He revealed, soon after His return from Tabríz, His denunciatory Tablet to Ḥájí Mírzá Aqásí. Couched in bold and moving language, unsparing in its condemnation, this epistle was forwarded to the intrepid Hujjat who, as corroborated by Bahá’u’lláh, delivered it to that wicked minister.