The principal aim of reading is to absorb knowledge and use the ideas behind the text to expand your lattice of connected ideas. It’s not to memorise random facts (unless your goal is to become a quiz master). Joseph Ledoux, a professor at New York University, believes ‘added connections are therefore more like new buds on a branch rather than new branches.”
The ability to grasp the gist of the text from an overblown book is the ultimate test that tells if you truly understand what you have read. So keep a pen in hand, and translate the text into your own words as you start to understand and connect ideas. This idea is also known as the Feynman Technique.
The time spent on rewriting the text is more valuable than the time spent on highlighting for coming back later or reviewing the same text multiple times. The act of viewing and re-reading doesn’t automatically make you learn. They only cram your short-term memory. They may be effective for passing exams but not for life-long learning. Apparently, Luhmann never reads the same text twice.
It’s not to say you should never visit the same text twice. You only go back to the original text when you find a new idea that contracts or compliments it. Going back again is not to re-read the original text. It’s to scrutinise and refine the previously learned facts, to develop them further, and to squeeze more juice out of the original source.