A Loan (n.) at interest struck Proudhon as an evil: selling the same thing again and again, collecting the price each time while never giving up ownership.
A Loan (n.) resembles labour-power in the capitalist's hands: both are bought for their use-value of producing more value than they cost — except that the loan's value is merely repaid, not paid.
A Loan (n.) reverses ordinary exchange: the money is on the side of the seller, and only one party gives out value.
A Loan (n.) outlives its banknotes: the notes stop circulating, but the debt remains, and unneeded currency drifts back to the issuer.
A Loan (n.) is a transfer from one hand to another that no sale mediates — so the same coin can serve thirty loans as easily as thirty purchases.
A Loan (n.) not mediated by any purchase creates no capital: £20 lent five times without buying anything is not £100 of capital but five claims of £20.