Wikipedia's overview: <https://en.wikipedia.org/wiki/Cyc>
Project / company homepage: <https://cyc.com/>
It's failure is no shade against Doug. Somebody had to try it, and I'm glad it was one of the brightest guys around. I think he clung on to it long after it was clear that it wasn't going to work out, but breakthroughs do happen. (The current round of machine learning itself is a revival of a technique that had been abandoned, but people who stuck with it anyway discovered the tricks that made it go.)
Cyc is sort of like that, but for everything. Not just a small limited world. I believe it didn’t work out because it’s really hard.
So you'd use the NN to recognize that the thing in front of the camera is a cat, and that would be fed into the symbolic knowledge base for further reasoning.
The knowledge base will contain facts like the cat is likely to "meow" at some point, especially if it wants attention. Based on the relevant context, the knowledge base would also know that the cat is unlikely to be able to talk, unless it is a cat in a work of fiction, for example.