One reason why European rulers are so keen on the euro is that it is meant to unite individual European economies into a larger bloc. But why does size matter?
Capitalism evolves through a cycle of recurring crises. At the end of each cycle the global economy emerges organised around successively larger units of capital.
Go back 200 years and a typical capitalist firm would involve a couple of factories owned by a family.
But by the middle of the 20th century firms were beginning to outgrow their national states.
Countries were too small to provide a domestic market or adequately represent corporate interests at a global level.
That is why regional blocs became so crucial for capitalists in small but industrially developed countries.
The European Union and the single currency are one manifestation of this. The Asean pact in South East Asia is another, as are South American regional blocs such as Mercosur.
This concentration of capital is part of a wider destructive cycle. Every boom creates conditions for a bust. Markets become saturated with goods and profit rates decline until it is more profitable to sit on money than invest it. The economy stagnates and firms collapse.
For ordinary people these downturns bring misery and despair. But for bosses they sow the seeds for eventual recovery.
Once enough capital has been destroyed or devalued the surviving capitalists can start again, cannibalising the remains of their former competitors.
With each recovery the economy is concentrated in fewer hands. Eventually units of capital become “too big to fail”. And when they do go bust, they drag whole economies down with them.