I want to know the answer to the following question:
What had previously kept prices stable?
All the background I'm provided with is that "The Federal Reserve, which was established in 1913, was designed to furnish an "elastic" currency subject to "substantial changes of quantity over short periods", which differed significantly from previous forms of high-powered money such as gold, national bank notes, and silver coins.". Is that enough to answer the question?
Answer: no