Fine-grained object model in hibernate

In the Hibernate in Action (Manning publication),

A major objective of the Hibernate project is support for fine-grained object models, which we isolated as the most important requirem开发者_如何学Pythonent for rich domain model. In crude term, fine-grained means "more classes than table".

I don't get this... Please some body help on this.

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This refers (I think) to what Hibernate calls "components", and what JPA calls "embedded classes". See the link for an explanation of what that means.