Exter's Golden Pyramid
It is a simple visualization of risk.
Gold has the most reliable value at the point, while asset classes on progressively higher levels are more risky.
The chart is also representative of the size of riskier assets in the world: the higher and bigger on the chart, the more of the asset there is worldwide and the greater its total value.
During boom times, money flows from the bottom of the chart to the top; during busts, money flows from the top to the bottom.