Is it better to concentrate on aggregate demand or aggregate supply? Why? According to Keynes, what are the major sources of economic instability? Fiscal policy is spending and taxation of the...

Is it better to concentrate on aggregate demand or aggregate supply?  Why?

According to Keynes, what are the major sources of economic instability?

Fiscal policy is spending and taxation of the executive branch of the federal government; in recessionary times, what initiatives in spending and/or taxation are going to help the economy?