Citations!
Citations blew my mind when I took Foundations of History as a freshman in college. If I found an idea that was interesting, there was a whole world of thinkers and writers who were cited and shaped or challenged that idea. This frame of thinking, thinking through the historiographical web, was a key skill that I gained as a member of a liberal arts undergraduate institution
I began to learn to always read the footnotes and follow the citations. I began to see knowledge as a web or a network, people built understandings of the world on top of each other. The structure of this digital garden is intended to mimic that kind of networked thought. You can see a visual representation of this network in the graph view on this site.