Obama says stimulus vital to avoid 'catastrophe' what does he mean by this?

Can we please have a president that is less vague and ambiguous about his planned actions. I don't understand what catastrophe is going to happen. We saw what happened with the last huge bailout under the similar cirstances. Changing the verbiage of what Bush said to get his stimuli-fail bill doesn't give you credit on your purposed bill. Thoughts, arguments, or any other information on this bill would be greatly appreciated.