This lecture deals not with the causes of the world financial crisis nor how to forecast or avoid one in the future, nor how to revive the financial sector, but rather with the crucial emergency "ambulance" policy of fiscal stimulus. What are the main effects of stimuli policies, and, in particular, the post-crisis effects? What are the main decisions to make and practical problems involved? What difference does a preexisting public debt problem make? Seven arguments against fiscal stimuli will be examined. Finally, fundamental ideological issues, namely government failure versus market failure, and fear of inflation versus fear of depression, will be noted.