driving force

The impetus, power, or energy behind something in motion, as in He was clearly the driving force in the new administration. This term transfers the force that sets in motion an engine or vehicle to other enterprises. Ralph Waldo Emerson was among the first to use it figuratively (English Traits, 1856): “The ability of its journals is the driving force.”

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.

Related Words for driving force

agenda, incentive, motivation, motive, reason, locomotion, propulsion, motivity

Examples from the Web for driving force

Historical Examples of driving force

Learning is only possible when instinct supplies the driving-force.
The Analysis of Mind
Bertrand Russell