Learning to crawl was hard work for Calvin. He could not hold his head up well if at all. His little arms were weak and he did not coordinate his movements much less understand why he had to. Down on all fours I supported his torso with one hand and with the other moved each limb in sequence - right arm, left leg, left arm, right leg - and so on. We rehearsed this unremittingly for months on end until we got results.
Calvin has never crawled very far or very well, but he crawls nonetheless. Even now it is sometimes, though rarely, his mode of transport. It is sheer delight to see him with a desired goal in sight and, with great enthusiasm, scramble to reach it.
I have become very fond of all of my holy jeans.