> You lend me 1,000 USD and then demand it back 12 months later. Can I give you 1,000 euro or 1,000 swiss francs instead? I doubt it. Both EUR and CHF are curr

> You lend me 1,000 USD and then demand it back 12 months later. Can I give you 1,000 euro or 1,000 swiss francs instead? I doubt it. Both EUR and CHF are currently worth more than USD, so that might not be the ideal example to make your point.