3 Verbs to Use for the Word mainspring

These capitalists are the mainsprings of the system; but we should no more apply their energy and skill to the detailed operation of so mechanical a structure as a railroad, than we should attach the mainspring of a watch to the hands directly, without the intermediate connecting chains and wheels.

He was wise, for he had seen a long succession of mechanical toys arrive to boast and swagger, and by-and-by break their mainsprings and pass away, and he knew that they were only toys, and would never turn into anything else.

It is to fail to observe that he has treated in his many books every mainspring of human action and that his themes have been the cardinal dreams and impulses which have in them heroic qualities.

3 Verbs to Use for the Word  mainspring