Concentration.................

 A million in the hands of a single banker is a great power; he can at once lend it where he will, and borrowers can come to him, because they know or believe that he has it.  But the same sum scattered in tens and fifties through a whole nation is no power at all:  no one knows where to find it or whom to ask for it.  Concentration of money in banks, though not the sole cause, is the principal cause which has made the Money Market of England, so exceedingly rich, so much beyond that of other countries.

-Walter Bagehot, from his 1873 book, Lombard Street:  A Description of the Money Market