A picture book is the one form where design is the writing. Paul Goble understood this better than almost anyone. The Girl Who Loved Wild Horses won the Caldecott in 1979 not only for what it says but for how it is made.
Goble worked in flat, brilliant color and precise line drawn from Plains traditions, arranging birds, flowers, and horses across the page with the care of a textile. You can hand the book to a child too young to read and they will still receive it.
That is what a Caldecott actually rewards: not illustration laid over a story, but a book conceived whole — an object made to be held, and returned to.