When I brought my third daughter, Josephine, to the pediatrician for her nine-month checkup, I reported that she had been sitting unassisted for nearly three months but that she was making no moves toward crawling. The doctor assured me that there was no cause for concern yet—babies all develop at different ages, and Josie's muscle tone looked fine. Maybe she was just a late crawler. Some babies skip the crawling altogether and go right to walking. Perhaps, the doctor said, we had one of those babies!
And while I like and trust my pediatrician, I did not think we had one of those babies. My other daughters had crawled at almost exactly nine months, and for a few months before that they practiced getting themselves into crawling position, rocking back and forth on their knees, making concerted efforts to get at something out of their reach.
Josie wasn't doing any of that. I had seen her roll a few times, but not very often, not very smoothly, and between you and me and the lamppost I think she was on a slight downhill when she did it. She wasn't trying to pull herself up. She seemed, for lack of a better term, completely unmotivated. Or, to put it in a more positive light, she was content to sit and play with toys and watch what was going on around her. Happy, yes. Making all the requisite baby noises. Engaging with her sisters in an age-appropriate manner. But completely stationary.