Comment by mhartl

Before people freak out about exponential growth, please consider John McCarthy's Slogan. (Yes, that John McCarthy; Lisp isn't the only thing he's done.)

  He who refuses to do arithmetic is doomed to talk nonsense.

http://www-formal.stanford.edu/jmc/progress/index.html

Based on reactions to this video (among other things), I'd add Hartl's Counterpoint:

  Just because you're willing to do arithmetic doesn't 
  mean you're not talking nonsense.

In case you're wondering why you shouldn't freak out, I offer you this: http://en.wikipedia.org/wiki/Logistic_function