The Federal Reserve's primary goal in buying Treasury bonds is to inject more money into the economy, thereby increasing the money supply and lowering interest rates. This is known as quantitative easing, and it is intended to stimulate economic growth by encouraging borrowing and spending. Lower interest rates make it cheaper for businesses and consumers to borrow money, which in turn can lead to increased investment and consumption. The hope is that this will create more jobs, increase economic activity, and ultimately lead to a stronger economy. Additionally, by buying Treasury bonds, the Fed can help keep interest rates low, which can make it easier for the government to borrow money to fund programs and services. Overall, the Fed's goal in buying Treasury bonds is to support the economy and promote sustainable economic growth.