Writing the formula down on a piece of paper doesn't by itself count as thought though. I haven't read the book so can't really comment what the author would say, but to load the formula into your brain and think about it in a useful way is very different than plugging it into a calculator or reading the formula.
Well, we have a generalized Euler's formula[1] for this identity:
Metaphorically, you can visualize the function e^(ix) tracing the unit circle out in the complex plane.[1]: http://en.wikipedia.org/wiki/Eulers_formula