I wish the author would have spelled out one, concrete, specific abstraction which he knew, which helped him understand Dijkstra's algorithm.<p>I propose an alternate explanation: The author found it easier to understand Dijkstra's algorithm the second time, <i>because</i> he struggled with it the first time.<p>And that is because there <i>is no</i> "lowest level." Anything can be explained in terms of something else--every word in the dictionary is defined using other words. We don't learn anything bottom-up like this, it's a more holistic process, a hermaneutic circle.