But why?

Lying in bed with me the other night... Duncan: Mom, why does everything in the world have a name? Me: Well I guess so we know what to call everything. Duncan: But why? Good question. How do you describe this to a four year old? I tried to go on to say, "well if things didn't have names we wouldn't know what to call them or how to "refer" to them"...but then he just asks "mom, what does "refer" mean? Sigh. It is just so beautiful to see his mind grow and I love these questions because it just means he is sucking life right up. But I honestly think the local college should offer a course in The Answers to your preschooler's "But Why" Questions so I can stop feeling so unbelievable inadequate.