Everybody knows the big Baby Book Milestones: first tooth, walking, first word. But the fun of being a parent is watching the gradual development of a full-fledged human being, in steps so tiny anybody else would miss them.
The other evening, DOB set D1 on her back on the bed, with a couple of stuffed carrots on her arms to keep her company. We expected her to pretty much flail her arms and ignore them. Instead, she grasped one of the carrots with both hands and patiently manipulated it until she had its nose (so some stuffed carrots have noses) in her mouth, and tried sucking on it. Whereupon she screamed in annoyance to find no milk forthcoming.
Now, this seems small. But consider all the development that goes into it. Not only is she aware that there is a world around her, she has come to the realization that she can manipulate and control objects in the world. She can form theories about what will happen and then test them to see if they will work. It's the beginning of all work and play, of hand-eye coordination, and of interacting with the world rationally, as a human being, rather than by instinct alone. She's made giant strides from the passive newborn of six weeks ago.
Of course, this deepens our speculation on whether she has figured out that parents are manipulatable, too.