Why?

I remember this being a joke amongst other parents but I've been experiencing it first hand the last couple of days.  What I'm talking about is at the end of every sentence you say to Josie, she asks "Why?".  What a curious little girl.  I heard her doing this to Jake yesterday morning and chuckled a bit as he went through various explanations, trying to work out the actual and most basic reasoning for each answer.

Jake: You have to put your shoes on.
Josie: Why?
Jake: Because if you go outside without your shoes on you could get an owie.
Josie: Why?
Jake: There could be something on the ground and you could step on it.
Josie: Why?
Jake: Because it might be sharp and poke your foot.
Josie: Why?
Jake: Just put your shoes on.

She started on me today, and it was all about going to the bathroom.  As I was explaining why we have to eat and then excrete, I wondered what would ever satisfy her questioning without just shutting her down?  Is there an answer she is looking for?  Could I ever come full circle in answering the reasons for things and we'd get back to where we started so she would understand the whole process?  I decided to let it go and time the question/answer session and see if we ever made it to the original point of discussion.  9 minutes later, after Josie using the bathroom, getting cleaned up, a fresh diaper and a snack, she became distracted by something else and stopped asking me.  Not really the result I was looking for but it was interesting to see that she would stay engaged for that long.  I doubt my patience or curiosity will last as long next time.