Most studies on early Isma'ilism have given considerable emphasis to the debate on the lineage of the Fatimid caliphs, whereas the origins of Isma'ilism's unique theological doctrines have gone relatively neglected. Rejecting the two prevalent depictions of Isma'ilism as either 1) doctrine faithfully transmitted since the 2nd/8th century or 2) a completely new doctrine emerging in 3rd/9th century, this presentation instead 3) argues for the vindication of earlier theories proposed by Massignon and Corbin in exploring Isma'ili doctrine's doctrinal dependency on the esoteric Imamism (commonly referred to as Ghulat Shi’ism) contemporary to its emergence. In fact, it will be demonstrated that the emergence of Isma’ili doctrine can only be understood in as an adaptation of Mukhammisa and Mufawwida forms of Ghulat Shi’ism. This will be illustrated by a brief survey on such shared doctrines as the Silent/Speaking Imam, the seven cycles of religion, the perennial hierarchy in religion, and the “tafwid” understanding of negative-theology.