The quiet power of writing
According to Sonke Ahrens (and likely Niklas Luhmann, the father of Zettelkasten), writing should be our default mode. In other words, we should filter our experiences and the information we encounter through the act of writing. To achieve this, we must use our own words. This is not only how knowledge becomes firmly established, but it also starts to truly become our own.
What accelerates our learning and growth is interaction with others. Through these interactions, we get the opportunity to verify, refine, and solidify our theories and ideas. The insight of the creator of the Zettelkasten method was achieving this effect... solo. Like playing an RPG with yourself, and yet the outcome is strikingly similar to what we gain through collaboration.
Writing allows us to compensate for the limitations that come with lacking interactions with others in building our worldview, as well as in learning and understanding. It becomes a powerful tool for constructing and reinforcing our knowledge.