I was pointing out that the complex explanation is that comets have their own driving force, and tides have a separate driving force, and planets have their own

I was pointing out that the complex explanation is that comets have their own driving force, and tides have a separate driving force, and planets have their own reason for moving as they do, etc. Compared to that kind of hodge-podge, relativity is still a really simple theory. While relativity increased the complexity of the explanation of gravity, it didn't bring it anywhere near the level of complexity that might have been assumed before Newton. The author's argument is that our intelligence is likely not solely possible by the interaction of a large number of separate principles, but rather by some simple principle that manifests itself in different ways. I think if we find some simple principle that explains intelligence, and then later have to make a correction to the math of that principle, the resulting explanation will still be simpler than the idea that intelligence is made up of many different principles all of which have to be present.