Visualise all the knowledge of the world as Mind Maps

I'm really looking for something along these lines and would appreciate some input: what's a good way to externally index one's knowledge (at least the "serializable" parts)?

Right now I have a few big org files that are already surprisingly helpful: I can use ag (SPC s a p on my Spacemacs config, I haven't bothered to rebind it properly yet) to search for, say, "pigeon", which leads me to Skinner's experiment.