In the second half of the 2nd/8th century, the Isma‘ili sect, who believed in the Imamate of Isma‘il, the second son of Imam Ja‘far al-Sadiq (A.S.), was formed. The Isma‘ilis brought up specific views concerning Imamate. From their point of view, the world of being can not survive a moment without the existence of an Imam and that mankind is always in need of a teacher, leader, and infallible Imam. The Isma‘ilis made great efforts to trace the existence of Imamate back to the beginning of creation. To this end, they presented special theories and interpretations of history and Prophethood. According to one of these theories human sacred history consists of seven periods during which mankind achieves perfection. Every period is formed by the emergence of a Prophet who is also called Natiq along with his Wasi (legatee) who is also called Samit (silent) or Asas (base). After them, seven Imams appear who attain Imamate one after another. Undoubtedly, Neo-Platonism has been influential in the formation of this idea. Natiq is the medium for the revelation of ordinances from God to people; Asas is the authority for interpretation of the ordinances; and Imam expresses the interior and the exterior of shari‘a (law). In the first six periods, Adam (A.S.), Noah (A.S.), Abraham (A.S.), Moses (A.S.), Jesus (A.S.), and Muḥammad (S.A.W.) were the law giving Prophets and with the coming of every new Natiq the previous shari‘a would have been abrogated. Of course, the ancient Isma‘ili sources were of divergent opinions on this issue.In order to better elucidate this issue, the Isma‘ilis have made specific esoteric interpretations of Imamate and the popularity of the number seven. This period of time, which is dedicated to each Natiq, may be a period of manifestation or a period of concealment; moreover, it may be a greater period or a lesser period, each one of which is explained in detail in this article.The present article addresses this issue with the use of the ancient theological and historical sources of Isma‘ilis.