It seems a simple question -- what is money?-- but the answer is more complicated than you'd think. In 1891, America's greatest self-made man, steel tycoon Andrew Carnegie, took on the subject in this essay. Here, he explains:

- the historical basis for money as a medium of exchange
- the difference between "money" and "currency"
- the trouble governments get into when they "make money"
- the problems that coming with backing currency with silver
- the "good sense" of the gold standard
- and more.

The ABC of Money: Lessons from a Tycoon offers a highly readable discussion of a basic concept of economics.

Also from Cosimo: Carnegie's Round the World, Triumphant Democracy, James Watt, An American Four-in-Hand in Britain, The Empire of Business, The Gospel of Wealth, and the Autobiography of Andrew Carnegie.