Sword Art Online Light Novel Volume 12

The twelfth volume in the Sword Art Online Light novel series and the fourth installment of the Alicization arc.

Chapter 7 (The Two Supervisors, 5th Month of Human World Calendar 380)
Kirito recollects his life since he entered highschool, and how he has been forced to leave his education three times already (one time because of the SAO incident, another time due to being stuck in Underworld and now again because of breaking the Taboo Index). He then resumes his talk with Cardinal  who continues the story of Quinella after she had found the list of system commands in Underworld.

She explains that when Quinella attempted to steal the system authority level from the Cardinal System using a complex system command, Quinella accidentally burned the primary instruction of the Cardinal System (to preserve regularity of the world) onto her Fluctlight as a non-changeable principle due to her low knowledge of the complex syntax of supervisor level commands. Because of this, Quinella inherited the Cardinal's duty of regulating the world, but pushed it to even greater extents - to regulate the residents as well.

It was Quinella who divided the human world into four empires and created different obstacles, such as the Gigas Cedar to restrict the movement of the residents and thus be able to regulate them. Then Cardinal proceeds to explain the origin of Quinella's worry and how she created the Synthesis Ritual to exceed the limit of her memory, which is estimaded to be about 150 years. The Synthesis Ritual allowed Quinella to manipulate the Fluctlights of a chosen person and thus she used this ritual to create a backup of her memories in another person's Fluctlight. That is how Cardinal came to be.