Machine Spirit

In the fictional universe of Warhammer 40,000, the Machine Spirit is a spirit believed by the Adeptus Mechanicus (and, from that source, by most other humans from the Imperium of Man) to inhabit and control a piece of machinery. The functioning or lack thereof of any machine is believed to be the result of its spirit's disposition. To keep their machine spirits happy and cooperative, operators therefore make numerous ritualised advances to their machinery. These depend on the machine, but in most cases include various maintenance rituals and occasionally also an offering or libation, if the machine is large or important.
Machine spirits are believed to be bestowed by the Machine God and subservient to him.

Because alien technologies do not make observances to their machine spirits, many among the Adeptus Mechanicus see them as grave heresies that must be destroyed rather than studied, even if superior to human-manufactured counterparts in operation. This view is not universal, however.

Artificial intelligence (or Abominable Intelligence, as it is known in the Imperium) is generally prohibited in the Imperium unless a human is combined with it or part of its circuitry. This is to ensure the AI does not rebel againts its human masters. However, some machines are allowed such an intelligence under the guise of having an especially active machine spirit. The best example of this is the Land Raider tank, which can continue to move and fire, albeit at a decreased capacity, even if its crew is unable to fight.