To this period of incarceration in the fortresses of Máh-Kú and _Ch_ihríq—a period of unsurpassed fecundity, yet bitter in its humiliations and ever-deepening sorrows—belong almost all the written references, whether in the form of warnings, appeals or exhortations, which the Báb, in anticipation of the approaching hour of His supreme affliction, felt it necessary to make to the Author of a Revelation that was soon to supersede His own. Conscious from the very beginning of His twofold mission, as the Bearer of a wholly independent Revelation and the Herald of One still greater than His own, He could not content Himself with the vast number of commentaries, of prayers, of laws and ordinances, of dissertations and epistles, of homilies and orations that had incessantly streamed from His pen. The Greater Covenant into which, as affirmed in His writings, God had, from time immemorial, entered, through the Prophets of all ages, with the whole of mankind, regarding the newborn Revelation, had already been fulfilled. It had now to be supplemented by a Lesser Covenant which He felt bound to make with the entire body of His followers concerning the One Whose advent He characterized as the fruit and ultimate purpose of His Dispensation. Such a Covenant had invariably been the feature of every previous religion. It had existed, under various forms, with varying degrees of emphasis, had always been couched in veiled language, and had been alluded to in cryptic prophecies, in abstruse allegories, in unauthenticated traditions, and in the fragmentary and obscure passages of the sacred Scriptures. In the Bábí Dispensation, however, it was destined to be established in clear and unequivocal language, though not embodied in a separate document. Unlike the Prophets gone before Him, Whose Covenants were shrouded in mystery, unlike Bahá’u’lláh, Whose clearly defined Covenant was incorporated in a specially written Testament, and designated by Him as “the Book of My Covenant,” the Báb chose to intersperse His Book of Laws, the Persian Bayán, with unnumbered passages, some designedly obscure, mostly indubitably clear and conclusive, in which He fixes the date of the promised Revelation, extols its virtues, asserts its pre-eminent character, assigns to it unlimited powers and prerogatives, and tears down every barrier that might be an obstacle to its recognition. “He, verily,” Bahá’u’lláh, referring to the Báb in His Kitáb-i-Badí’, has stated, “hath not fallen short of His duty to exhort the people of the Bayán and to deliver unto them His Message. In no age or dispensation hath any Manifestation made mention, in such detail and in such explicit language, of the Manifestation destined to succeed Him.”