The Rivera Manuscript, also called the Praxis Manuscript, was an important war prediction that described a renegade's imprisonment by an unknown power and his subsequent praxis-induced vision of the devastation of the Homeworld.
The Manuscript was first recorded in the possession of Diego Rivera, who received it as a gift from a female companion (likely a model or lover) shortly before his departure from the United States in 1933. During this time, he showed it to Argentinian writer Jorge Luis Borges, who read it and compared it unfavorably to the Saragossa manuscript. Despite beginning a series of sketches based on the Manuscript, Rivera lost or sold it shortly after his arrival in Mexico.
Isabel Allende later referenced the Manuscript as a personal possession of her uncle Salvador right before he was elected President of Chile. Though it was believed destroyed in the fascist coup of 1973, a few years later it resurfaced behind a filing cabinet in the American Library of Congress. It was verified as authentic by the handwritten note to Rivera on the cover.
An American private collector owned the Manuscript until, toward the end of the century, Faction Paradox made a deal to buy it; when the seller broke the deal, the Faction instead stole it and moved it to the archives of the Eleven-Day Empire, where it became one of the Faction's most paradoxical artefacts and a subject of extensive study. (PROSE: The Book of the War)
The Manuscript was a typed transcription of another document. Three-quarters were written in an untranslatable language, with several sections written in symbols apparently designed to convey statistical data. The remaining quarter had been translated into English and gave a first-person account of a renegade's imprisonment by agents of an unknown power. Though the Manuscript never directly described the captors, it alluded to a humanoid form, a non-carbon presence, and something the renegade called "the first, the many, and the indivisible".
The Manuscript began with a brief action-packed description of the renegade's capture before shifting into a description of a series of praxis-induced alternate time-states, apparently guided by an interrogator who had also entered the fugue and may have written the document as a report for its superiors.
In the longest section of the report, the renegade found himself at a familiar site on the Homeworld: a prominent chapterhouse in the foothills of the mountains at the edge of House society. With him was a person, perhaps the interrogator, referred to only as "One"; throughout the Manuscript, the narrator would occasionally make mostly-incoherent asides directed at "One", such as, "Why does it hate us?"
In the vision, the renegade began to approach the chapterhouse, but was met and arrested by a group of guards who explained that it was under telepathic attack. While the renegade argued with them in an attempt to investigate, "black fireball"s materialised out of the sky and crashed into the chapterhouse and other nearby Houses. The Manuscript spent thirty pages describing the fireballs with telometric data; the renegade baselessly speculated that they were "supercharged chunk[s] of the causal nexus itself".
The guards and the renegade ran into the chapterhouse's smoking remains to search for survivors. The renegade befriended a female servant who described how the lords of the Household had been spontaneously overwhelmed by seizures, and he theorised that the attack's first wave was directed to corrupt the Homeworld's noosphere. Several survivors were still insane and uncontrollable, attacking anyone nearby, so the sane survivors gathered in an intact loomshed.
The renegade predicted that the next wave would attack the timeships, and indeed there was a suggestion that several stolen timeships had returned to the Homeworld, detonating ecstatically upon materialisation. However, the real next attack came out of gauges in the sky where column after column of Ashla shock-troops began to descend upon the planet, many of them within two miles of the chapterhouse. The group of survivors, now led by the renegade, were able to capture an advance guard, but they spontaneously combusted before they could be questioned.
The subsequent siege of the loomshed lasted for several days, the breeding-engines screaming continuously. The renegade speculated that the next and final attack would be directed at the Houses' engineered sun and power source, but when the enemy forces finally invaded the loomshed, they headed straight to the breeding-engines, plunging straight into the machinery and self-detonating. This left the looms intact but mutated. Then, before the renegade could speculate about this new attack, the enemy finally neutralised the power source. The entire Homeworld vanished into cataclysm.
After this, a new phase of the praxis fugue began. Several other sequences were described in the Manuscript, including one set inside the Homeworld's sun; the regressive sequence seemed to represent a fight between the renegade and his interrogator. At one point, the renegade had a brief conversation with "One", the interrogator, or both. (PROSE: The Book of the War)
Is that what you're planning / It might be / It still could be / Remember / Inside the skin of the sun / It's an option / It wouldn't work / What if someone tried it / What if you were called to account / It's an option / Always an option / You keep the sun / In a bottle / You want to know what happens if you lose control / Don't you?
At the end of the Manuscript was a hand-written note, written in English but not by a human hand, that predated Rivera's companion's note on the front. It read, "Praxis is not a drug. Praxis is not a weapon. Praxis is not a training manual. Praxis is what we were meant to become." (PROSE: The Book of the War)
The events described in the Manuscript didn't match the actual beginning of the War in Heaven in several important details: most importantly, the enemy never used Ashla shock-troops, and the initial attack completely failed to destroy the Homeworld. (PROSE: The Book of the War)