At a time when the Cause of the Bab ...

 "At a time when the Cause of the Bab seemed to be hovering on the brink of extinction, when the hopes and ambitions which animated it had, to all human seeming, been frustrated, when the colossal sacrifices of its unnumbered lovers appeared to have been made in vain, the Divine Promise enshrined within it was about to be suddenly redeemed, and its final perfection mysteriously manifested. The Babi Dispensation was being brought to its close (not prematurely but in its own appointed time), and was yielding its destined fruit and revealing its ultimate purpose -- the birth of the Mission of Baha'u'llah. In this most dark and dreadful hour a New Light was about to break in glory on Persia's somber horizon. As a result of what was in fact an evolving, ripening process, the most momentous if not the most spectacular stage in the Heroic Age of the Faith was
now about to open.

During nine years, as foretold by the Báb Himself, swiftly, mysteriously and irresistibly the embryonic Faith conceived by Him had been developing until, at the fixed hour, the burden of the promised Cause of God was cast amidst the gloom and agony of the Síyáh-Chál of Tihrán. "Behold," Bahá'u'lláh Himself, years later, testified, in refutation of the claims of those who had rejected the validity of His mission following so closely upon that of the Báb, "how immediately upon the completion of the ninth year of this wondrous, this most holy and merciful Dispensation, the requisite number of pure, of wholly consecrated and sanctified souls has been most secretly consummated." "That so brief an interval," He, moreover has asserted, "should have separated this most mighty and wondrous Revelation from Mine own previous Manifestation is a secret that no man can unravel, and a mystery such as no mind can fathom. Its duration had been foreordained."
 
Shoghi Effendi, God Passes By."