The belated "Why?"s

I thought someone once told me that the neverending "why?"s started at the age of three. Maybe I'm remembering incorrectly. Because now, at age 4 1/2, Nicole is all about the "why?". Occasionally she'll throw a "how come" in there, but it's all the same.

So anyone with a four year old (or if you went through this at 3), what the heck is the answer? I knew this was coming, and I was dreading it. But at the same time, I really thought I would be a brilliant mommy and answer her questions so satisfactorily, that one "why?" would be sufficient. I was so incredibly wrong.

Tonight, I was just tired, and come bedtime, couldn't answer any more why questions. So I said that the two bedtime stories would have to be from her very small books. Good thing too, because every page (like, all 8) had the endless string of questions.

I finally answered "Because that's what it says in the book". Brilliant, I know. *smirk*. But my clever answers just aren't doing the job.

So I want to know. What's the best way anyone has ever answered "why?". I'm looking for the answer to end all. The one that makes the four year old simly say "oh" and roll over and go to sleep.