The Chu construction: history of an idea.
The genesis of mathematical structures, as exemplified in the work of Charles Ehresmann
Three themes in the work of Charles Ehresmann: local-to-global; groupoids; higher dimensions
This paper illustrates the themes of the title in terms of: van Kampen type theorems for the fundamental groupoid; holonomy and monodromy groupoids; and higher homotopy groupoids. Interaction with work of the writer is explored.