I am aware of the motives of finding a modification of Newtonian mechanics, but the effects of relativity are so subtle and negligible. How in the world was he able to even find it? Even at speeds of the Earth orbiting the Sun, the effects are almost negligible. I know he started out with a thought experiment, but it still astounds me. I've read his original papers, but still does not explain how he was able to do it without experimental data. What was his general step by step process in coming up with the theory?