The Motive Force is the sacred energy revered by the Adeptus Mechanicus as a manifestation of the Machine God's will, the divine current that animates machinery and grants motion to the works of mankind. To the tech-priests, electricity and the flow of power are not mere physical phenomena but holy forces, expressions of the Omnissiah made manifest in the turning of gears and the crackle of energy.
Every cogitator, engine, and weapon is held to be quickened by the Motive Force, and its channelling is attended by elaborate ritual, unguent, and prayer. A tech-priest who awakens a dormant machine believes he is coaxing forth a spark of the divine, guiding the Motive Force into a vessel prepared to receive it. The Galvanic weapons wielded by the Skitarii are said to channel this holy current directly against the foe.
To the priesthood of Mars, understanding the Motive Force is to draw closer to the Machine God itself. It is the animating breath of all technology, the sacred pulse that separates the blessed working machine from the profane inertia of dead metal.