Other diagrams followed. Understanding the structure of reality is a step by step process. It is similar to a jigsaw puzzle when one has not seen the finished picture. The puzzle is completed only when every piece finds its place. Each piece informs how it fits with other pieces.
Pieces mesh into sections.
Sections eventually join to show the whole picture. The analogy comes full circle by substituting scientific facts for puzzle pieces. Pieces represent evidential facts. Scientific understanding relates one fact to others. Physics principles enable a systematic arranging of the diagrams into a hierarchy to represent what physics is all about the structure of reality.