2. Galilean principle of relativity and Newtonian mechanics Historical background? Let's begin with some historical background so you can understand relativity a little better. It will probably be easier for you to understand if I tell you how the theory of relativity originated. by the way, since I'll gloss over some details, I hope you'll forgive me if my explanation lacks a little scientific precision. First, more than 300 years before Einstein made his appearance... well, I guess it's okay as long as I get the general idea. ...there was the Galilean Principle of Relativity discovered by Galileo Galilei. Relativity... principle? What Is Relativity? 17