Every time when a crisis casts shadow over the economy, all the economists seem to remember about “long forgotten” Keynesian theory. Although just a few economists think about themselves as traditional Keynesians, the economic policies inspired by Lord Keynes are still alive. For instance, the fundamental goal of any central bank is to avoid inflation which means to assure prices stability. Is not this the Keynes ideal: economic progress with full employment and fixed prices? Let’s take a look of the current subprime crisis. The best solution found by FED is to cut the interest rate and to cheapen the loans. If Keynes will be alive he surely would be delighted by the FED’s acts. The purpose of this paper is to analyze the Keynesian theory of prices in order to find the extent in which the solutions found by Keynes are still valid.