I never heard of Spherical Horses.
I studied physics using the classic Halliday and Resnick book (GREAT book).
Now I was a math major. I understood that you prove everything!
1st chapter in H-D they state a fact that they claim is usually true.
Then they stated another theorem and proved this one! But they proved this theorem using the (unproved) theorem before this. I thought hey this is not right!
But after that they did not do that silliness anymore. Starting off a book like that (and a classic one at that) really left a bad taste in my mouth.
To be honest, I do love Physics but I loved math much more.