Being taught by a 4 year old

This morning, Boo and I were sitting on the couch talking and the room got noticably darker. "What happened mom?" she asked, "it got darker in here." "It is okay," I replied, "the sun went behind a cloud." "Mom," Boo said in her most serious 4 year old voice, "the sun doesn't move, it CAN'T go behind a cloud. Only the clouds move. The clouds would have to move in FRONT of the sun. Actually, that means it will probably rain. When the clouds are dark and they block out the sun, it will probably rain. You have to say the clouds made it darker by moving in front of the sun, not that the sun moved behind a cloud." She actually kind of laughed at the end, like I was SO crazy for what I said. I sat their dumbfounded. SHE'S 4!!! My bigger question is, if she knows all that... WHY DID SHE ASK ME???