To better handle the themes of cosmic horror of a Call of Cthulhu style game, Liberporus uses the sanity system as it appears in the D20 Call of Cthulhu RPG. Aside from seeing terrible things the PCs must also learn horrible, mind-shattering truths. These are their teachers thus far:
Codex of the Vnspeakable One: Written in Phoenician, it is a collection of rituals used by the Brotherhood of the Yellow Sign to please their terrible diety.
The Trve and Secret History of the Brotherhood in Liberportvs: A history of fall of the Valossan civilization due to the rise of of the worship of a being called Xasthur and the Yellow Sign. The codex then glosses over the next few centuries and picks up in mordern Liberportus. It tells of the survival of the serpent men of Valossa who remained hidden underground bideing their time until they could release the power of their dread god once again. The copy of this book in the PC's possession was meant to be found and used as justification for the attack on the priests of Minerva in Terror in Liberportus.
Blood of The World: Written in Etruscan, it is a scroll concerning itself with the practical and theoretical study of alchemy. No information is given in the scroll about the writer, whence his knowledge came from, or any other alchemical texts.
The Diary of Paramezzvs Svllo: The Diary of Paramezzus Sullo contains a record of the madman's alchemical experiments and the formulas for his nefarious creations. It also details his exploration of old Etruscan ruins and the indescribable horror he met upon his discovery of the ancient tome Blood of The World.
The Way of the Yellow Sign: A very vague and metaphor ridden explanation of the being known as the Unspeakable One and why it should be worshipped. Very difficult to read and often leaves the reader with a sense of nausea.
Carcosa: or, The Queen and The Stranger: A play by Estus Talbus, adapted from the play Adventus Regis by the late Livius Carbo. It is a dreamy, confusing play that affects all who view it differently. Its subject is the Political situation in the City of Yhtill and the arrival of a Stranger, an unheard of event. The Stranger heralds the coming of The King in Yellow, an apparently malevolent entity who dooms the city in an unspecified way by transforming it into Carcosa.
The Wanderer by The Lake: Written by Alexander Pulcher, it is a puzzling tome written in both Parthian and Latin describing a dreamer's travels to and throughout Carcosa.
The Trajan Codex: Wrtten in the time of Marcus Ulpius Nerva Traianus Augustus, the codex is a collection of oaths and prayers made to the Magnum Innominandum so that one may gain the benefits of the Unspeakable Oath.