Just One Dark

I woke Harry up for school the other day, and he was having his usual hard time coming around. I finally got him out of bed and took him to the changing table in Rachel's room, like usual. He started asking his thousand questions, as usual, mostly about playing baseball outside.

The conversation went something like this:

Harry:  Daddy, is it too dark outside to play baseball right now?

Dad:  Yes, Harry, it is too dark to play baseball.

Harry:  It is very dark out, isn't it, Daddy?

I looked out the window at this point, and noticed that it really wasn't that dark, the sun had just started to come up.

Dad:  No, Harry, it's not too dark.

Harry gave me that look that told me the wheels were spinning, he was really thinking about something.

Harry:  Is it just only one dark, Daddy?