The mainspring is vanity, assisted by the love of garlic and bread and butter.
He resisted the navy, the mainspring of Washington's foreign policy; he opposed commercial treaties and diplomatic intercourse in a similar fashion.
The chief objects of his study, however, were the works of Chrysippus, opposition to whose views is the mainspring of his philosophy.
It was in every way fitting, however, that he who had been the mainspring of the war from the beginning, and had borne far more than his share of its burdens and discouragements, should end it with the campaign of Yorktown, conceived by himself, and the surrender of Cornwallis (October 1781).
Conduct like this, though obviously disinterested, did not go without immediate and ample reward, in the public confidence which it created, and which formed the mainspring of Pitt's power as a statesman.