The principle that a central bank, charged with controlling inflation, should be independent from the government is unassailable. It may also be true that it's easier for the central bank to guard its independence from political pressure when it mainly holds government securities.

In this quote, Janet Yellen emphasizes the importance of independence for central banks, particularly in the context of their responsibility to control inflation. The principle that a central bank should operate independently from the government is considered fundamental for maintaining its ability to make decisions based on economic conditions, rather than political pressures. Yellen suggests that maintaining autonomy allows central banks to prioritize long-term economic stability over short-term political goals.

Yellen also highlights the relationship between the central bank's ability to maintain its independence and the types of assets it holds, particularly government securities. By holding these securities, the central bank can be less susceptible to political interference, as its financial interests are closely tied to government debt, which could reduce the likelihood of external pressures from the government or political figures seeking to influence its decisions.

The mention of government securities reflects a nuanced understanding of the central bank's operations. When a central bank primarily deals with government securities, its policy decisions and financial health are often aligned with the fiscal policy of the government, yet it retains the flexibility to act independently when needed. This ensures that the bank can focus on price stability and managing inflation without being swayed by political agendas.

Ultimately, Yellen's statement underscores the critical role that independence plays in a central bank’s effectiveness, especially in its mission to control inflation. She also suggests that while this independence is vital, the central bank’s financial structure, such as holding government securities, can offer practical safeguards that help protect its autonomy from political pressure.