INTRODUCTION.

In our preliminary Discourse, we have therefore traced back to the primitive religion of humanity; we investigated whether there were peoples among whom it was preserved or perfected; finally, we followed the human spirit original: "l’esprit-humain" through the changes it imposed upon this religion up until the birth of Christianity.

At that point, we treated each century as a distinct era; we presented the ideas, customs original: "mœurs," referring to the collective social habits and morals of a people, tastes, and philosophical principles of that age, and we demonstrated how these causes gave rise to the heresies, schisms, and sects Sects: in this historical context, referring to organized religious factions or splinter groups that troubled the Church during that period, as well as their impact on civil states.

Having laid out the birth, succession, and blending of these errors and sects, and the kind of warfare they waged against one another—displacing and destroying each other, so to speak, up until our own century—we then made each heresy the subject of a specific Memoir Memoir: a detailed historical treatise or monograph focusing on a single subject. In these, the reader can grasp at a glance the state of the human spirit regarding the Christian religion at the time of a heresy’s birth, as well as the causes that produced it; one can follow its course without interruption, observe its effects on religion or civil society, and see it spread with brilliance, establish itself, be extinguished, be reborn under a thousand different forms, or give birth to other errors that cause it to be forgotten.

To this history of heresy—or, if I may put it this way, this history of how passions and prejudices maneuver to defend a...