Today I was making soup. Elliot was sitting in his bouncy chair, bouncing irritatedly. He was a little bored. And I wanted to finish the soup before I took him out of the chair. So I got him a toy from the other room. I held it out to him, and he considered it. Upon further reflection, he took the toy and put it thoughtfully in his mouth.
Now, none of this is a particularly dramatic skill developing. Grabbing, mouthing; he's been doing this stuff for a bit now. But today it occured to me: holy crap! He can grab and mouth. He can be bored, and then interested. He's a person in there.