When I taught a macro course 20 years ago at UT-Chattanooga, we used Wallace Peterson's book which quoted Keynes as though it were Holy Scripture. Not surprisingly, Paul Krugman now seeks to justify his "space aliens" nonsense with...a quote from (Who else?) Keynes.
I will let readers view his post, but keep in mind that Krugman also thinks that he has effectively demolished the idea of gold being legitimate money. (According to Krugman, gold is a "useless metal," which I suspect is his way of saying that people use scarce resources to dig up something "useless," which, I guess, means that they are idiots.)
Furthermore, the use of gold bars in the "basements of central banks" is a relatively recent phenomenon and has little to do with the historical role of gold being used as a medium of exchange as opposed to a basis for issuing paper. But, given what I have read of Krugman, he would take it that we should leave gold in the ground (except for jewelry) because paper is being managed by Really Smart and Serious People like Ben Bernanke.