One of the gifts of the Jewish culture to Christianity is that it has taught Christians to think like Jews, and any modern man who has not learned to think as though he were a Jew can hardly be said to have learned to think at all.
Seeing that he owns absolutely nothing to ‘repay’ his debt, ‘his own consciousness’ of the fact ‘that he is himself the very substance’ of debt, so must he ‘repay’ with himself, so must he ‘return’ himself to Him Who owns him absolutely.