The Ascent of Man from 1973 has been one of my favorite tv series ever. I got a book based on that series as a matriculation gift. Browsing through the book yesterday I found an elegant proof of the Pythagoras' theorem.
On this video clip from the tv series Jacob Bronowski explains why the right angle has been so significant to our civilization. He also shows how Pythagoras may have proved his theorem using tiles and a branch of an olive tree!
