Cash: Fiat currencies are designed to depreciate in value over time. In fact, $100 in 1800 is worth only $8 today, representing a loss of 92% of value. Burying cash in coffee cans in your yard is a terrible long-term investing plan. If it manages to survive the elements, it will still be worthless given enough time.
Bonds: Historically, good, quality bonds tend to return 2% to 4% after inflation in normal circumstances.
Business Ownership, Including Stocks: Looking at what people expect from their business ownership, it is amazing how consistent human nature can be. The highest quality, safest, most stable dividend-paying stocks have tended to return 7% in real, inflation-adjusted returns to owners for centuries. That seems to be the figure that makes people willing to part with their money for the hope of more money tomorrow. Thus, if you live in a world of 3% inflation, you would expect a 10% rate of return (7% real return + 3% inflation = 10% nominal return).