Twenty-seven letters

The manifestation of twenty-five out of the twenty-seven letters which all the Prophets were destined to reveal refers to the Báb, the promised Qá'im, and inscrutable and wondrous events (e.g., shocking martyrdoms)

"No understanding can grasp the nature of His Revelation, nor can any knowledge comprehend the full measure of His Faith. All sayings are dependent upon His sanction, and all things stand in need of His Cause. All else save Him are created by His command, and move and have their being through His law. He is the Revealer of the divine mysteries, and the Expounder of the hidden and ancient wisdom. Thus it is related in the "Biháru'l-Anvár," the "'Avalim," and the "Yanbú'" of Sádiq, son of Muhammad, that he spoke these words: "Knowledge is twenty and seven letters. All that the Prophets have revealed are two letters thereof. No man thus far hath known more than these two letters. But when the Qá'im shall arise, He will cause the remaining twenty and five letters to be made manifest." Consider; He hath declared Knowledge to consist of twenty and seven letters, and regarded all the Prophets, from Adam even unto the "Seal," as Expounders of only two letters thereof and of having been sent down with these two letters. He also saith that the Qá'im will reveal all the remaining twenty and five letters. Behold from this utterance how great and lofty is His station! His rank excelleth that of all the Prophets, and His Revelation transcendeth the comprehension and understanding of all their chosen ones. A Revelation, of which the Prophets of God, His saints and chosen ones, have either not been informed, or which, in pursuance of God's inscrutable Decree, they have not disclosed, — such a Revelation these mean and depraved people have sought to measure with their own deficient minds, their own deficient learning and understanding. Should it fail to conform to their standards, they straightway reject it. "Thinkest thou that the greater part of them hear or understand? They are even like unto the brutes! yea, they stray even further from the path!"[ Qur'án 25:44.]

"How, We wonder, do they explain the aforementioned tradition, a tradition which, in unmistakable terms, foreshadoweth the revelation of things inscrutable, and the occurrence of new and wondrous events in His day? Such marvellous happenings kindle so great a strife amongst the people, that all the divines and doctors sentence Him and His companions to death, and all the peoples of the earth arise to oppose Him. Even as it hath been recorded in the "Káfí," in the tradition of Jábir, in the "Tablet of Fátimih," concerning the character of the Qá'im: "He shall manifest the perfection of Moses, the splendour of Jesus, and the patience of Job. His chosen ones shall be abased in His day. Their heads shall be offered as presents even as the heads of the Turks and the Daylamites. They shall be slain and burnt. Fear shall seize them; dismay and alarm shall strike terror into their hearts. The earth shall be dyed with their blood. Their womenfolk shall bewail and lament. These indeed are my friends!" Consider, not a single letter of this tradition hath remained unfulfilled. In most of the places their blessed blood hath been shed; in every city they have been made captives, have been paraded throughout the provinces, and some have been burnt with fire. And yet no one hath paused to reflect that if the promised Qá'im should reveal the law and ordinances of a former Dispensation, why then should such traditions have been recorded, and why should there arise such a degree of strife and conflict that the people should regard the slaying of these companions as an obligation imposed upon them, and deem the persecution of these holy souls as a means of attaining unto the highest favour?"

(Bahá'u'lláh, Kitáb-i-Íqán, par. 272-273)

"In a communication addressed to the American believers I have in the course of my explanation of the station of the Báb made a passing reference to the incomparable greatness of the Revelation of which He considered Himself to be the humble Precursor. He Whom Bahá'u'lláh has acclaimed in the Kitáb-i-Íqán as that promised Qá'im Who has manifested no less than twenty-five out of the twenty-seven letters which all the Prophets were destined to reveal-- so great a Revealer has Himself testified to the préeminence of that superior Revelation that was soon to supersede His own."

(Shoghi Effendi, World Order of Bahá'u'lláh, 100)

Besides its main meaning in referring to the great power of the Cause, this prophecy also refers to advancements in material knowledge of this age

"In the Shí`í tradition concerning this dispensation it is recorded that knowledge is composed of twenty-seven letters and that the divine messengers of the past from first to last have revealed but two letters; however, when the promised Qá'im comes, He will appear with all twenty-seven.

"Aside from the true meaning of this passage which pertains to the power and might of the Cause of God, to the revelation of verses and signs, to the solution of divine problems, to the disclosure of the mysteries of the Holy Book and to the spread of knowledge -- each of which is a hundred times greater in this mighty revelation than in any previous one -- materially, too, all the learned men of this age agree that the advancements in knowledge, the arts, industries and inventions of this century are equal to those of the last fifty centuries, indeed, even greater than that.

('Abdu'l-Bahá, Mahmúd's Diary, in New York, June 12 (or 13?), 1912)

Not to be interpreted literally; indicates relative greatness and superiority of new Revelation

"Regarding the passage beginning with the words: 'Knowledge consists of twenty-seven letters': this should not be interpreted literally. It only indicates the relative greatness and superiority of the new Revelation."

(From a letter written on behalf of the Guardian to an individual believer, July 10, 1939, in Lights of Guidance, no. 1607)