Size matters. That is the lesson to draw from Washington’s debt ceiling debate and the downgrade of its sovereign credit rating by Standard & Poor’s, neither of which drove up US bond yields. It is also the lesson to draw from Japan, which combines the world’s lowest bond yields with one of its largest public debt stocks.

This lesson has a plain implication for eurozone countries: they should pool their debts – with or without Germany’s participation. The benefits from creating a debt market of a size to rival those of the US and Japan would clearly outweigh the costs.

Size underpins the affordability with which these states can borrow. The total stock of US government securities outstanding is $9,500bn (€6,600bn). For Japan the figure is Y875,000bn (€7,900bn). Even adjusting for the share of obligations held by the two countries’ public sectors (especially Japan), the tradable stock is enormous. Indeed, it is virtually impossible for investors to avoid these bonds. So they do not: they are currently willing to fund Washington for 10 years at 2.3 per cent and Tokyo at 1 per cent a year.