The article shows that when banks hold more cash instead of lending it out, it can hurt the economy. This happens because banks are less willing to give out loans, which affects how much people spend and invest. The researchers used a model to study how this "precautionary liquidity shock" impacts the economy. They found that it leads to lower output, consumption, investment, and prices. This effect is stronger when there is more long-term risk in the economy and when banks are more sensitive to potential risks.