6 ideas
The money view treats every economic agent as a node whose cash inflows must cover its cash outflows each day, a requirement Mehrling calls the survival constraint. Seen this way, a crisis is not a failure of real fundamentals first. It is a failure to meet payment obligations when funding liquidity dries up, and the price of that liquidity decides who survives.
In a market-based credit system, credit flows through dealers who make markets in securities, so the central bank's backstop must extend to markets, not just banks. When private dealers stop making markets, the central bank steps in to put a floor under asset prices. It does this by buying assets or lending against them, which keeps the securities market-liquid so they can go on serving as collateral.
Money is organized as a hierarchy of promises: gold or central bank reserves at the top, then bank deposits, then securities, each a promise to pay the layer above. In a crisis the hierarchy contracts and everyone scrambles for the higher, scarcer forms. This means the central bank's job is to manage how elastic and how disciplined the system is at each layer.
The central bank's core task is to balance the elasticity of credit, meaning letting it expand to smooth payments, against the discipline of settlement, meaning forcing obligations to be met. Its tool is the price and quantity of its own liability. Too much elasticity breeds speculative excess. Too much discipline turns liquidity shortages into cascading defaults, so the policy lever is the terms on which the survival constraint is relaxed.
Through them it lent to primary dealers, swapped Treasuries for illiquid mortgage securities, and bought commercial paper outright. Its balance sheet ballooned as it took onto itself the shadow banking system's funding of capital-market assets, acting in substance as dealer of last resort.
The shadow banking system financed long-term capital-market assets with short-term wholesale funding such as repo and commercial paper. It relied on derivatives like credit default swaps to make that funding look risk-free. The arrangement assumed market liquidity would always be available, so when asset prices fell, funding liquidity and market liquidity collapsed together in a self-reinforcing spiral.