The Meccan Revelations: Page 59 from Volume One

The principles of the unknown surahs do not know their reality except those who have reasonable forms. Then he made the surahs of the Qur’an with the Sīn, which is legitimate worship, and it is the apparent surahs in which there is torment and in which ignorance of them falls, and its inner meaning is with the sad, which is the place of mercy, and there is nothing but knowledge of its truths, which is monotheism, so He made it, Blessed and Most High, twenty-nine surahs, which is the perfection of the form and the moon. We have decreed it as stations, and the twenty-nine is the pole by which the sphere is sustained, and it is the reason for its existence, and it is Surah Al Imran, the Name of God. Had it not been for that, the twenty-eight would not have been established, and its totality on the repetition of letters is seventy-eight letters, so the eight are the reality of a few.

Peace be upon him said, “Faith is seventy-few,” and these are The letters are seventy-eight lette