Lydia reaches her arms to me as I step outside to open the garage for the bicycles the kids will ride to school. There’s still a bit of baby fat on her cheeks. I kiss them and inhale her familiar scent. I’ve been parenting long enough to know she’s just doing the hard work of growing up, and that we are all feeling her growing pains. I also know that we are all kinder, more generous and more creative because of this baby. I love her more than anything in the world. I would lay down my life for her. Standing on my tiptoes to enclose her older sister in a sandwich hug (“I’m the lettuce!” Lydia cries), I try to forgive myself the dark thoughts. I can be impatient, imperfect, sleep-deprived and immature sometimes, and still be a good mother. Sooner than I can stand it Lydia will be the willowy teen heading off to middle school. Only she’ll have no baby sister waving her goodbye.