Mainsprings [noun]

The outer end of the mainspring is attached to the rim of the barrel, and the inner end to the barrel arbor.

Unless this double mainspring is known, the conduct of Catherine de' Medici will remain forever misunderstood.

To such religion was the mainspring which kept the whole intellect going; and religion was to be had at the meeting.

All the old restraints were wanting, and self-interest alone formed the mainspring of action.

Fingering is the mainspring, the determining principle, one might almost say the life and soul, of the pianoforte technique.

The mainspring of her early life was to please, and of her later life to make people happy.

In losing this friend of thirty years Madame Récamier felt that the mainspring of her life was broken.

Since it was too small to depend on weights, it contained a coiled mainspring—something entirely new to the clockmaking world.

The mainspring of the old system had become a simple anomaly to the new radicalism.

Cal'late my head must have stopped goin'; maybe the shock I had a spell ago broke the mainspring.