I once heard a teacher say that she wasn’t allowed to test on anything that had to do with Algebra in her Geometry class because the vice-principal had said it wasn’t fair to do so since they are different subjects. Had she paid any attention to him, she wouldn’t have been able to test on anything since the two are really the same thing – one gives a visual representation of the other. She said she just kept on doing what she had been doing. The guy had shown such a profound lack of understanding on the subject, she doubted he would be able to tell the difference. I recently read a book about Descartes (the guy who unified Algebra and Geometry) and was reminded of this moment so I thought I’d share. If you have any interest in the history of Mathematics, consider reading a book or two by Amir Aczel. Man is this guy a great writer or what? If you do read his books, I’d say a good place to start is “Fermat’s Last Theorem”, though it was his “Descartes’ Secret Notebook” that inspired this post.