Growing too fast.

For a few months now, I've begun to realize that Nathaniel is growing from an infant to a baby. I know that he doesn't look this this any longer:

In my mind, I think that Nate is probably around 6 months old. I think that he just learned to sit up, and he's just started to eat pureed vegetables. And, he looks like this:

Yesterday, I took my baby outside onto the deck to eat his afternoon snack. I sat him down close to the house so that he couldn't fall backwards and hit his head, and then I made the mistake--I glanced away. When I looked back, my little baby was gone! In his place was this little boy:

When did he get so big?!