In 1944, at the Bretton Woods Conference, Keynes, an eminent economist, proposed Keynes Plan, applying bancor as the unit in settlement and accounting among different currencies. It is the first time in the history of human currency that the concept of super-sovereign currency appeared, offering a rudiment for world currency. Although the plan had been discarded, it showed a feasible solution to our world currency system.
That's utter rubbish - probably taken from whatever website you lifted that piece of text from.
The
Trade dollar (United States coin) was just one example from the 19th Century that toyed with the idea that a (usually) one ounce coin in bullion metals (usually gold or silver) would be worth the same across borders regardless of the denomination marked on the surface.

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