To describe a particular food, while dieting, you think naturally in terms of its protein, carbohydrate, and fat content.

Thus, the numbers that describe a particular food constitute a natural bundle—a bundle of three numbers for each individual food.

In this chapter, you learn that one of Smalltalk's great virtues is that Smalltalk offers programming-language mechanisms that enable you to describe, construct, and manipulate bundles of descriptive data items that mirror real-world individuals and groups of individuals. These special mechanisms set Smalltalk apart from most other programming languages.