Matta was born in 1,314 BYZ in the Old Exekian Empire. He was a scholar and alchemist known for his obsession with death, a concept largely foreign to his kind. In particular, he was interested in the biological and psychological differences between Exekians and humans.The curiosity-driven Matta amassed a vast library at his home, Casca Dun. His endless thirst for knowledge led him throughout the known world and prompted him to embark on countless experiments, the nature of which were sometimes considered ethically questionable. Later in life, he adopted Kemet, an aisling, as his ward.In an effort to preserve life, he began seeking a "cure" for mortality. Eventually he created an "elixir of life", which he believed would render the imbiber immortal. One of his human servants, Cordelia, agreed to be a test subject and ingested the elixir. The experiment failed horrifically, resulting in the instant death of the subject. Cordelia perished "as if she had swallowed poison".
Disillusioned, Matta sank into religious fanaticism and ultimately came to the conclusion that the humans were in fact superior beings to the Exekians, because they could die and thus achieve "spiritual apotheosis". His theory was denounced and he was publicly ridiculed.Freeing his slaves, Matta arranged for their safe passage to Dardanos, only to have his plans foiled by border guards, who recaptured them. Under torture, one slave revealed Matta had intentionally freed them, resulting in a scandal. Emperor Rokanan had Matta brought before him for an explanation; when Matta announced his anti-slavery beliefs, Rokanan banned his writings and blacklisted him from academic circles.With his reputation ruined, Matta forged a new identity, taking on the name Arkady (after the famous soothsayer) and offering his services as an overseer, using Kemet's power as a front. He was hired by Caspar, a wealthy elite and political protege of Rokanan. Matta knew Caspar was being groomed to be Rokanan's successor; the young politician was brutal in his treatment of mortals. He enlisted the aid of Kemet, who dreamwalked, manipulating the dreams of the slaves in order to plant rebellious ideas in their minds and rally them against their master. Kemet deliberately presented himself as Matta in their dreams, inspiring their loyalty to their turncoat overseer.
The brief uprising they inspired resulted in the assassination of Caspar and the attempted murder of Rokanan himself. Those who participated in the revolt were interrogated under torture and subsequently executed, and Matta became a wanted fugitive on the run.
He was finally cornered in the ruins of a fortress, where he wrote much of his memoir. The manuscript was inscribed on crystal tablets, a technique Matta had developed himself through alchemy.
Since he had deliberately portrayed himself as Matta in dreams, the slaves never mentioned Kemet's involvement. The emperor assigned Kemet to track down Matta. Despite his reluctance, Kemet slew his adopted father in the early hours of the morning in the spring of 230 BYZ. Before he struck, Matta had him vow to protect his manuscript and take control of his property.
Matta's estate included his massive library, which contained original copies of the Mandorlin. These documents were later used as the basis for Vormund's new, accurate version of the Mandorlin, translated by Kemet and published in the year 162. The "Book of Matta", which revealed the truth about the conflict, was included in this collection, appearing in print for the first time 392 years after Matta's death.