R.G. Hawtrey viewed business cycles as purely monetary phenomena caused by fluctuations in bank credit and money supply. He argued that expansions are caused when banks lower interest rates and expand credit, stimulating borrowing by traders. This leads to increased production, income, spending and demand in a self-reinforcing cycle. Contractions occur when banks tighten credit due to depleted reserves, raising rates and curbing borrowing. This causes falling demand, income, production, prices and profits in a deflationary spiral. Hawtrey saw uncontrolled credit as the root cause of instability, and argued that controlling credit would regulate economic fluctuations.