You're looking for information about the "Sefer HaRazim" PDF.
: Often hosts public domain or academic scans of Michael A. Morgan’s widely cited English translation, Sepher Ha-Razim: The Book of Mysteries .
From an academic perspective, Sefer HaRazim is invaluable. It provides a snapshot of "folk Judaism" or "popular religion" during the Talmudic era, showing a worldview where demons were tangible threats and angels were bureaucratic functionaries who could be petitioned. It challenges the modern assumption that ancient Judaism was purely legalistic; here, we see a vibrant, if somewhat syncretistic, engagement with magic.
Its modern rediscovery is thanks to the brilliant scholarship of in the mid-20th century. While examining thousands of manuscript fragments from the Cairo Genizah (a storeroom of discarded Jewish texts in Egypt), Margalioth recognized recurring themes and styles. He meticulously pieced the fragments together, publishing the first reconstructed Hebrew edition in 1966.