Mentat: the human mind built as a computer

A Mentat was a profession and a discipline developed to replace the computers and thinking machines outlawed by the Butlerian Jihad, which forbade the making of any machine in the likeness of a human mind. In the same way that the Bene Gesserit and the Spacing Guild took up functions once served by the thinking machines, the Mentats became living calculators, their minds trained into instruments of cognition. Dune's glossary describes them as the class of Imperial citizen trained for supreme accomplishments of logic, human computers. (Dune)

Origins after the Jihad#

In the aftermath of the Butlerian Jihad, computers and thinking machines were outlawed under the commandment against making a machine in the likeness of a human mind. Reverend Mother Mohiam tells Paul that the Great Revolt forced human minds to develop and that schools were started to train human talents. The Mentats, like the all-female Bene Gesserit and the Guild's Navigators, took up work the machines had once done. (Dune)

Frank Herbert never says who trained the first Mentat. Brian Herbert and Kevin J. Anderson give the honour to Gilbertus Albans, the human raised by the robot Erasmus, who shows the capacity first and goes on to found the Mentat School. (Expanded books: Dune: The Battle of Corrin; Mentats of Dune)

The discipline#

The role of Mentat demanded both natural ability and strict conditioning. Mentats were not merely calculators. Thufir Hawat in Dune is master of assassins as well as Mentat, and both Hawat and Piter de Vries weigh probabilities and motives as much as numbers. Hawat is also training Paul as a Mentat. (Dune)

The Mentat works by projecting from data to probable outcomes, a kind of logic that can come close to prescience. The Duncan Idaho ghola Hayt is trained as a Mentat by the Tleilaxu in Dune Messiah, and Miles Teg is the Bene Gesserit's Mentat Bashar in Heretics of Dune. (Dune Messiah; Heretics of Dune)

Dune's glossary describes sapho as a high-energy liquid extracted from barrier roots on Ecaz, used by Mentats who claim it boosts their mental powers. Users develop deep ruby stains on the mouth and lips, and Piter de Vries is marked that way. (Dune)

Service to the Houses and the Sisterhood#

In Dune the Great Houses keep Mentats as advisers and spymasters: Thufir Hawat serves House Atreides and Piter de Vries serves the Harkonnens. After Hawat is captured, the Baron keeps him alive because a Mentat of his quality is too useful to waste. Paul Atreides also has Mentat training. (Dune)

The Bene Gesserit also trained Mentats among their own Reverend Mothers. Tertius Eileen Anteac is a Mentat in God Emperor of Dune, and Bellonda, who keeps the Sisterhood's archives, is one in Chapterhouse: Dune. (God Emperor of Dune; Chapterhouse: Dune)

Twisted Mentats#

The Bene Tleilax trained Mentats of their own, without the limits that bound ordinary ones. Piter de Vries, the Harkonnens' twisted Mentat, is the most infamous of these, a man who enjoys pain and plans the destruction of the Atreides with relish. (Dune)

Suppression and survival#

The reign of Leto Atreides II as God Emperor brought new pressure on every old order, the Mentats included, as he held the spice melange in his own hands for three and a half thousand years in pursuit of the Golden Path. The Mentat art survived him. The Bene Gesserit kept Mentat training alive, and Anteac is one of theirs in God Emperor of Dune. (God Emperor of Dune)

After the Scattering, Mentats are still at work: Miles Teg trains the new Duncan Idaho ghola, and Bellonda serves Mother Superior Odrade. (Heretics of Dune; Chapterhouse: Dune)