wrote

But Kepler's laws are so essential, you say. OK, fine.

They're essential for making a good impression on a perfect stranger. I
think I once related a story here that, as I was walking down a mountain
path near Tucson, a fellow was coming up the path and he looked at me.....
and asked, "Do you know Kepler's Laws?" Ummm... well, yes, I do! And I
proceeded to draw them out in the dirt with a stick.