What's that got to do with the price of butter?
Necessary But Not Sufficient by Eliyahu M. Goldratt
Naked Objects by Richard Pawson
From a business perspective I want a group of classes that mirror real world items e.g. Order, Invoice, Address, Amount, Price, Date etc. Then I want another group of classes that handle business actions e.g. Enter Order, Print invoice. Lastly a group of classes that handle business process e.g. Process Order, Calculate invoice etc.