animal spirits

1 sometimes animal spirit obsolete :  the nervous energy that is the source of physical sensation and movement

2 :  vivacity arising from physical health and energy

3 in Keynesian economic theory :  emotional feelings and desires (such as an optimistic willingness to take positive action) that influence the economic behavior of consumers and investors If you ask how much consumers will consume and investors invest over the next few months, the answer is determined largely by feelings—what John Maynard Keynes called “animal spirits.” If frightened people decide not to spend, their nervousness can translate into a depressed economy. — Paul Krugman