A violent incursion by the saecular world into one or more maths. Generally, the term is capitalized only when referring to one of the three Great Sacks, during which virtually every math was overrun. There are also records of local sacks, when one individual math or concent was overrun, but these are of lesser importance.
The First Sack took place after some Maths developed newmatter technology. In the Convox following the Sack, further research into newmatter was prohibited. Avout were permitted a limited number of newmatter technologies, including their bolt, chord and sphere. In addition, the special recording disks used in their telescopes were permitted.
The Second Sack took place after some Maths developed advanced genetic manipulation technology. Subsequent to this Sack, all Maths were forbidden all praxis (technology), including syntactic devices (computers), as well as any further research into genetics. However, a number of results of genetic manipulation were retained, including a number of special plants such as library grapes. Some plants, such as the Eleven which are forbidden by the Discipline, typically because they have psychotropic effects, were also the result of pre-Sack genetic manipulation. The Ita, who also originated at this time, were permitted to use praxis within the Maths while the Avout were not.
The Third Sack was the most dramatic, and resulted in all Maths except for the three Inviolate Millenarian Maths left vacant for around seventy years. Many Avout were killed. Their clocks, however, kept time during this period. This sack took place after the development of Polycosmic manipulation by certain thousander Maths. The Halikaarnian orders developed manipulations named in legend as Incanters and the Procian orders were named in legend as Rhetors.
After the Third Sack, the practice of dowments, a form of property ownership passed down via a lineage was forbidden in the Mathic world. Furthermore, the various Orders were split up, so that many Orders would have Chapters at several different Concents. However, towards the end of the novel in a conversation between Erasmas and Emman Beldo, it is speculated that the mysterious Old Lineage was the only new thing that was "grandfathered in" after the Third Sack.