The Didact's sigil.

The Didact was the supreme commander of Forerunner military forces during the ancient Diluvial War. He was a member of the rate of Warrior-Servants, and specifically of their highest class, translated as the Prometheans. One of the best-documented Forerunner figures, his activities are known to us mainly through the terminal dialogs, a set of messages exchanged between the Didact and his wife, the Librarian.

Biography

A staunch believer in the Forerunners' Mantle to protect life, the Didact was firmly against the Halo Array, viewing the weapons as a crime beyond measure. During the war against the Flood, he led numerous campaigns against the Flood, adopting increasingly drastic measures over the course of three centuries to delay the parasite's spread. From early on, the Didact championed the Shield World strategy as a means of creating armored habitat-worlds for sector populations to evacuate into and from which to carry out military campaigns against the Flood. In this he would often clash with the Master Builder, the architect of the Halo solution, and a bitter rivalry existed between the two. The Didact would often debate the continued relevance of the Mantle and the Array's morality with his wife, the Librarian, who traveled across the galaxy to archive sentient species in preparation for the Halos' firing. The Didact attempted to convince the Librarian to abandon her work and return to the safety of the Jat-Krula line, believing she was putting herself in needless jeopardy. His pleas fell on deaf ears, however, as the Librarian remained committed to her moral imperative to preserve life.

In the final decades of the war, the Didact and his former political enemy, the Master Builder, created Mendicant Bias, a powerful AI intended to take the fight to the Flood's controlling intelligence, the Gravemind. However, the Mind convinced Mendicant to turn against its masters instead, consigning all military assets at its disposal to the Flood. It was around this time that the Librarian discovered the primeval Earth, and willingly stranded herself there after sending its sentient biota to the Ark. The Didact prepared to dispatch a rescue party to retrieve his wife and bring her to the safety of the Ark. However, the rampant Mendicant Bias breached the Line, and destroyed the awaiting rescue party. Devastated, the Didact resigned himself to the very inevitability he had fought for so long, activating the Array from the Ark, sterilizing the galaxy of life and stopping the Flood. What happened to him since is a matter of some ambiguity, but surviving testimony by the Didact speaks of embarking on a "Great Journey" and entering a long sleep in the quiet of space.

In the Covenant religion

The Didact is one of the most popular deities of the Covenant pantheon, as several surviving records associated with him remain. The most notable of these is the epic poem known to the Covenant as the Kandonom Codex. In the Covenant common language, he is named Pfuranth, literally meaning "Teacher" or "Didact", though he is often called by the epithets Shurmat-Umal, the Willful Mentor, and Orran'thet, the Daring One. In Covenant iconographic tradition, the Didact's cynosure or devotion-image is of a robust angular design, and bears the mark of the "Branching Tree"; the colors bronze, gold and red are associated with him.

Worship of the Didact is one of the oldest cults within the Covenant religion, predating the Covenant itself among the Sangheili. In Covenant religious traditions he is associated with warfare, leadership, oratory, teaching, war-poetry and will, and is seen as a patron of warriors and leaders. In Covenant doctrine, it is said that the Didact wished to delay the firing of the Sacred Rings so that the younger races may longer be graced with the Forerunners' presence; some traditions also assert that the Didact wished to devise alternate tools of salvation. As a result, Didact cults tend to favor Many Paths traditions such as the Path of Many Increments, believing that the Great Journey may be initiated through relics other than the Sacred Rings. He is also sometimes associated with the Sovereign Instrumentality school, which teaches that while the Forerunners should be worshiped, they should be held as exemplars and emulated rather than copied directly, for they claim that to take apart and copy Forerunner relics is blasphemous. In their view, the Forerunners expected the younger races to develop their own tools of salvation and are not worthy to take shortcuts to the Journey by defiling the Forerunners' creations. This tradition actually has its roots in one of the pre-Covenant Sangheili religions, and while it remained popular in the Covenant's first millennium, it would later fall out of favor as the Covenant's dogma took shape. It still continued in some parts of the Holy Ecumene, and has seen a resurgence within the Concord of Reconciliation and its semi-affiliated religious reconciliatory body Mending Communion, as well as various other post-war polities.

The Sangheili often prefer to see their martial culture and philosophy as following the Didact's example, though in reality very few descriptions of Forerunner military practices remain. In particular, one of the oldest Zealot chapters, the Daring Ones, was founded in homage to the Didact and his Prometheans, as the Forerunner root word for "Promethean" has to do with daring, will and defying commonly accepted conventions and/or standards.