As for the "jungle puzzle" look and feel, it is corollary to the solution: to keep exchange services in high demand and income in fatty amounts, you must build ships, bulwark a bridgehead in Holy Land, deploy supply lines over the Mediterranean sea, op-research the schedules of the shuttling ships, trim their cargo, sails, and course, dodge storms and squirts of Greek fire, fill log books, quarantine the sick, cook for the healthy, fill immigration forms, patrol the desert in steel combat boots, fill accounting books, balance them, carry them around in auditing campaigns & what not. And you, the would-be banker, cannot subcontract this jungle crawling & content yourself withcrawl while presiding boards of directors in the 13th C. equivalent of tailcoat & silk hat; you must exert your own person to each taskof those tasks from the noblest to the meanest, on pain of acquainting nosy outsiders of your private agenda.