The dependency structure between packages must be a directed acyclic graph (DAG). That is, there must be no cycles in the dependency structure.
包之间的依赖结构必须是一个直接的无环图形（DAG）。也就是说，在依赖结构中不允许出现环（循环依赖）。

Packages that are maximally stable should be maximally abstract. Instable packages should be concrete. The abstraction of a package should be in proportion to its stability.
最稳定的包应该是最抽象的包。不稳定的包应该是具体的包。包的抽象程度跟它的稳定性成正比。

The dependencies between packages in a design should be in the direction of the stability of the packages. A package should only depend upon packages that are more stable that it is.
一个设计中的包之间的依赖应该朝着稳定的方向进行。一个包只应该依赖那些比自己更稳定的包。

The classes in a package should be closed together against the same kinds of changes. a change that affects a package affects all the classes in that package.

The classes in a package are reused together. If you reuse one of the classes in a package, you reuse them all.