You worry too much about every little speck of dust in this house.

That was what Natalie said to me while she dropped her keys into the ceramic bowl by the front door, right before we walked back to the nursery. Lily was six months old then, sitting in her bouncy seat and kicking her fat little legs against the fabric. I had spent the morning washing bottles, scrubbing the kitchen floor on my hands and knees, and making sure every toy was wiped down with safe soap.