The mainspring is vanity, assisted by the love of garlic and bread and butter.
A recent critic has sought in religion the clue to her character and the mainspring of her genius.
She works from within outwards, touches first the mainspring and then sets it to play.
This author is indeed interested to prosecute vigorous and substantial thinking, but the mainspring of his interest is the conviction that such thought is significant for inner and outer life.
mainspring of positive social change.