Go into any bank. Ask the manager "At the end of the day do your books balance?" and I will guarantee he will tell you they do. Between the start of the day and the end he might have issued $1,000,000 in loans (without a single dollar in cash crossing the counter). The paper he exchanged for the loans balance the loans given. The value is in the signature of the people promising to repay the loans. Interest payments unbalance the books.