It has all been done by postage stamps.

When the financial world suddenly tightened up in 1907 a wholesale
dry goods house found itself hard pressed for ready money. The
credit manager wrote to the customers and begged them to pay up at
once. But the retailers were scared and doggedly held onto their
cash. Even the merchants who were well rated and whose bills were
due, played for time.

The house could not borrow the money it needed and almost in despair
the president sat down and wrote a letter to his customers; it was
no routine collection letter, but a heart-to-heart talk, telling
them that if they did not come to his rescue the business that he
had spent thirty years in building would be wiped out and he would
be left penniless because he could not collect _his_ money. He had
the bookkeepers go through every important account and they found
that there was hardly a customer who had not, for one reason or
another, at some time asked for an extension of credit. And to each
customer the president dictated a personal paragraph, reminding him
of the time accommodation had been asked and granted. Then the
appeal was made straight from the heart: "Now, when I need help, not
merely to tide me over a few weeks but to save me from ruin, will
you not strain a point, put forth some special effort to help me
out, just as I helped you at such and such a time?"

"If we can collect $20,000," he had assured his associates, "I know
we can borrow $20,000, and that will probably pull us through."

The third day after his letters went out several checks came in; the