What topic do you think is essential/interesting for people to read about?

I'm planning on reading more this year, and a reading style that works for me is reading by topic (syntopic reading). So the idea came to me:
Why not ask the Redditors?

I'm open to suggestions ranging from universal ones that you consider essential for everyone (in your opinion) to know — geopolitics, philosophy — to the most diverse, interesting (in your opinion), and specific ones possible — Complex Systems and Epistemology, The Origin of Fantasy, color theory — and if you also know of any books on the aforementioned topic, I'd be more than happy, but I'm already happy with the topic.