Thudding and thunking with the weight of a lesson to be learned, this homily in picturebook form will work best with those who like encouragement straight up. ""This is how Emily grew from not-being-able, to now-she-can,"" begins Slepian (The Mind Reader, 1997, etc.). She masters small feats: pouring milk (from a bottle--the details are all nostalgic in this book) on her cereal without spilling, going down the twisting slide. When she becomes too fearful to stay all night at her grandmother's house, and must be driven home at 10:00, ""It's all right, my honey,"" her grandmother says. ""Someday you'll stay the night and think nothing of it."" After three failures, Emily succeeds. Coalson's watercolors offer homey details, full of humor and whimsy; there's a terrific portrait of the older Emily eating crackers and reading in bed. But those young enough to appreciate the lesson may find it more sublimely served in Rosemary Wells's dear Edward the Unready tales (Edward's Overwhelming Overnight, 1995).