Varoufakis' book contains some arguments and explanations. I don't have the book in English with me, so this is a 'free translation' of a couple of points (bold is mine):
"Contrary to the entrepeneur, the banker does not organize production. (...) We're wrong to think that he is an intermediary between those with excess money and those who wish to lend that money (...). Before, it was like that. Centuries ago. Now, only in very rare occasions does the banker have that role. (...) In developed market societies, the banker does not obtain existing value (money) from some to then give it to others. He obtains it from the future, so that it's possible to use it in the present. (...)"
['Talking to my daughter about the economy', Chapter 4, section 'The "hand" of the banker']
He later, on the same chapter, goes on to say:
"Every society has its legends. Market society is no exception. The fundamental legends of our time are these four:
- Bankers lend money from savings accounts deposits.
Finally, later on (Chapter 5), when listing reasons for why people can't get loans after a crisis, he lists some reasons:
"First, because banks won't lend them money, since they are themselves based on money that they don't own, that is, the debts of private parties and the State to them, which will never be payed."
What does he mean by 'banks lend money from accounts' being a legend?
I am admitedly very naive about economy in general (hence what may seem a very ignorant question) but I was always under the assumption that banks make money by charging higher interest from the money they lend then they pay people for their savings accounts. What is this 'borrowing from the future' mechanism that he describes?
Finally, doesn't the last bit contradict that? If banks can 'make up' money 'from the future', why do they depend on the money from the debts of people, companies and the State?