Keynes's letters to President Franklin D. Roosevelt clearly illustrate Keynes's firm belief that the main policy to help the US economy recover in a sustained way from the Great Depression was through increased public investment. In 1938 Keynes wrote to Roosevelt:

In an earlier letter to the president, in 1933, Keynes had written,

This is still, or even more, the case now. It was, to an important extent, true after the so-called Global Financial Crisis of 2007–09 and the subsequent eurozone debt crisis; it is also true in what seems to be, unfortunately the far worse current Covid-19 crisis.

One of the modern ways of increasing public, as well as private, investment is through funding by public development banks. By working with private banks and private capital markets, as well as other public institutions, public development banks can add leverage to public resources. Such leverage, facilitating a counter-cyclical response, is particularly valuable in times of economic crisis. Second, and crucially, public development banks provide valuable policy steering to help channel significant financial resources to key priority areas, such as the urgent green transformation and more inclusive growth.