Each concept here is mapped to its prerequisites — the ideas you'd need first to understand it — all the way down to four foundations: Space, Time, Energy, Pattern. Click any prerequisite to drill down, or scroll for the chain graph.
When water's essential properties as a transparent, tasteless, odorless liquid composed of hydrogen and oxygen molecules, and its capacity to support the construction of structures like ships, come together to create a sheltered space that protects ships from the elements, a harbour emerges.
External reference — all senses of the word “harbour” on Wiktionary. This atlas concept maps to only the slice of meaning relevant to the prerequisite graph.