INTRODUCTION 9
The more famous of the heresiologists include Irenaeus of Lyon, whose major
work was Adversus haereses, "Against Heresies"; Hippolytus of Rome, who
wrote Refutatio omnium haeresium, "Refutation of All Heresies"; Pseudo-
Tertullian (an author writing under the name of Tertullian), who wrote Ad-
versus omnes haereses, "Against All Heresies"; and Epiphanius of Salamis, who
authored a particularly nasty piece entitled Panarion, "Medicine Chest," with
an orthodox remedy for every heretical malady. The neoplatonist philosopher
Plotinos of Lykopolis also wrote a heresiological treatise, Against the Gnostics,
according to his student Porphyry. All these heresiologists focused, to one ex-
tent or another, upon the supposed gnosis of the heretics, and they suggested
that at least some—even if only a few—of the heretics could be called gnos-
tikoi, gnostics, or referred to themselves as gnostikoi. While these heretics used
the word gnosis, they did not necessarily call themselves gnostics. Irenaeus
wrote five volumes against heresies, and he claimed to have composed an "ex-
pose and refutation of falsely so-called knowledge." Irenaeus and his fellow
heresiologists, motivated by a religious zeal to expose and refute people with
whom they disagreed, were rather sloppy and imprecise in their use of terms
and their enumeration of heresies. Yet their presentations of gnosis, "falsely
so-called gnosis," have played a role, albeit a polemical one, in defining the
terms gnosis, gnostic, and gnosticism in modern discussions.
The widespread use of the word gnosis (and similar words in other lan-
guages, for example, in Coptic and Latin), and the polemical application of
this word and related words among the heresiologists, have created a challenge
for scholars and students who wish to understand gnosticism. What is gnosti-
cism, the religion of gnosis? Gnosis is a word widely attested in the ancient
world, but the word gnosticism itself is a term not attested at all in antiquity or
late antiquity. Rather, it first was used in the eighteenth century to designate
the heretical religious groups discussed by the heresiologists. Are gnosticism
and gnosis valid categories for analysis? Who actually were the gnostics? These
questions have become even more interesting when scholars have reflected
upon gnosticism and gnosis in relation to hermetic, Mandaean, Manichaean,
Shi'ite, and Cathar religions. Further, the discovery and publication in recent
times of primary texts (as opposed to the secondary texts of the heresiolo-
gists) generally considered to be gnostic has raised the issues of definition and
taxonomy in new and exciting ways. Among these primary texts are those
from the Askew Codex (Pistis Sophia, or Faith Wisdom), the Bruce Codex, the
Berlin Gnostic Codex 8502, and the Nag Hammadi library. The Nag Hammadi
library is a treasure trove of Coptic texts, most previously unknown and manyi