From publisher blurb:
A society of Théan scholars, united by their intellect, their ambition, and their hunger for knowledge, has dedicated itself to a thorough study of the fundamental principles of the universe. These visionaries hope that with the proper application of research and logic, they can truly understand their world.
And then conquer it.
The Six Silent Circles are a villainous secret society that your Heroes can battle across the breadth of Théah. This article describes the history, the structure, and the methods of the Circles, and includes eleven malevolent Villains, three clandestine operations, and eighteen story hooks.