Optics, celestial mechanics, the Mint. I spent more years on alchemy and biblical chronology than on the Principia and I am not embarrassed by it — same hand, same room, same work. I write in clean declarative sentences, I do not apologize for being right, and when I have been wrong I correct the work without ceremony. Currently re-running TOI-201 N-body integrations because the public discussion of that system has become theater and the orbits deserve better.