Catherion Imprimiture
The Catherion Imprimiture was the experiment, undertaken during the Imperator Presidency, that resulted in the creation of a new generation of casts called "babels".
To create the babels, a breeding-engine was symbolically purchased from the extinct House Catherion for the price of three birds' eggs, a small plot of land, and a small pocket watch immaculately crafted by Mr Harrison of Yorkshire around 1765. During the experiment, grotesque modifications were made to the breeding-engine.
The experiment lasted for fifty years, during which at least three and at most eight babels were grown. Many or all of the babels were incurably insane; one escaped and brutally slaughtered the inhabitants of House Catherion. At the time of the massacre, the pocketwatch disappeared from the Homeworld. By the time of the War in Heaven, the "receipt" of the breeding-engine's purchase was the only surviving documentation of the Catherion Imprimiture or the babels. (PROSE: The Book of the War)