Houdini

Yesterday morning I got Stone out of his crib and put him on the floor with a few toys. I hobbled out to the kitchen (I have 2 sprained knees) to make some coffee, and when I came back in he was four feet away from where I put him.
Hmmm.
Upon closer observation, it became clear that Stone is now capable of moving
BY HIMSELF.
Okay, so he scoots backwards, and he's not setting any speed records, but I still feel like something changed yesterday.
Like life as I know it.