From the Middle Ages to the present goetia is the term for a branch of magic which conjures or summons spirits, especially demonic ones, demons. The term comes from classic Greek, goeteia, which was the art of the goes, originally a ritual mourner at funerals–goes is an archaic Greek word for a lament for the dead–and later, according to literary sources, became a necromancer who had the capability to call spirits back from Hades. Much later goes meant «sorcerer,» and magic of every description till it developed a strong negative connotation until magicians avoided the term insisting that they were not goetes.
However, ritual for summoning various types of spirits has been a vital part of classical magic as witnessed in the Greco-Egyptian magical papyri. With the disintegration of the classical world and the advancement of the Middle Ages the practitioners of these rituals formed subcultures, first in the Muslim cultures, and later in medieval Europe.
Although, hard to believe, the spread of goetic magic occurred within the Christian church itself. There formed a secret, loosely knit underworld of magical practitioners of priests, monks, and clerics. The knowledge of Latin accompanied with the familiarity of the exercise of exorcism gave these clerics the necessary background, and the secretive literature of the grimoires provided the rituals and technical information. Judging from contemporary literature the goetic underground was securely in existence by eleventh century and by 1200 was active throughout Western Europe. It survived the constant pressure of the church through the Middle Ages and substantially contributed to the magical synthesis of the Renaissance.
Practice of Goetic Magic was widespread during the Renaissance but waned as did the other occult practices with the coming of the Scientific Revolution in the seventeenth and eighteenth centuries. However, since many goetic writings promised wealth the magic in the underground stayed alive even during this period. Prominent Christian figure dealt in some severe blows but it has achieved more widespread use with the rise of non-Christian and anti-Christian sentiment, especially within the twentieth century. A.G.H.
Greer, John Michael. The New Encyclopedia of the Occult. St. Paul, MN, Llewellyn Publications. 2003. pp. 201-202