At the moment I am reading the biography of Otto Warburg eloquently written by Hans Krebs. Here is a nice story about the banking house M. M. Warburg in Hamburg: Aby Warburg renounced his right to share in the banking business on the condition that his brothers would pay the bills for all the books that he deemed necessary for his library. The brothers enormously underrated the magnitude of this financial obligation – Aby Warburg (1866-1929) assembled a unique art history library which is now at London University. Would you like to have a brother who is a banker or would you like to be a banker with such a brother?