Each is a new stage of abstraction. Here we come to a crucial point. There are two great engines driving thought, simplification and abstraction. We seek to construct ideas that are simpler and thus more unique. And we seek to construct ideas that are more abstract and thus more unique.
Artifacts are unique when they are different and when they are the same.
When we seek simplicity we are searching for difference. When we seek abstraction we are looking for sameness. The essential tools for the construction of knowledge, sameness and difference are also the essential tools that drive thought. To simplify is to group together, to fashion sameness in our artifacts. To abstract is to differentiate, to separate, to define a difference from other artifacts.