This weekend at a family gathering, my 45-year-old cousin, a new father, walked into the room with his sleeping baby girl on his shoulder. He said to another cousin, "Want to feel the best feeling in the world? Want to let Aimee sleep on your shoulder?" He transferred the little girl to his aunt's shoulder, and the baby nestled into her new position. I enjoyed watching both of my cousins reveling in the sweetness of a baby, totally relaxed and trusting, sleep on their bodies. I remembered the days when it was my husband's and my turn to experience that with our sons. It's a heart-swelling, quiet kind of joy.…