Given the protean nature of literary genre, the question "What is a children's book?" has long been regarded as intriguing if possibly unanswerable, almost to the point of teleology: a children's book is "a book which appears on the children's list of a publisher" (Townsend 10). An equally complex but perhaps more fruitful query is "What enables an author to write both children's books and adult fiction?" Is this skill a matter of authorial personality, marketing, or a serendipitous synthesis? And what provokes the crossover?
Certainly, the list of authors who have published in both genres is long and distinguished. In They Wrote for Children Too, Marilyn Fain Apseloff has catalogued over a hundred "adult" writers whose works have also included children's texts (admittedly, sometimes adapted by later writers). But in fact the number of authors famous in both genres is far more limited. What links a book like Ian Fleming's Dr. No with his Chitty Chitty Bang Bang?
Those who write for both children and adults tend to fall into one of three categories (not including hybrids, exceptions, and bad examples). The most common category comprises writers of adult fiction who, for one reason or another, take up children's literature in mid-career. This pattern mimics the general history of publishing: an enterprise importuned by or otherwise made aware of a new audience for its goods. Unfortunately, some modern adults' authors think that all they must do to appeal to children is write pablum versions of their regular material. Those who manage the transition gracefully may have learned something about children: sometimes the impetus for a first children's book is the author's first child. Such authors may also have an intuitive grasp of children's psychology, in some cases an arrested adolescence of sorts. Another possibility in this category is an author who writes on themes appealing to readers of diverse ages. Roald Dahl is a good example of this type; so, for that matter, are such seeming opposites as Antoine de Saint-Exupéry and Fleming. But it is not an easy achievement, and each year's list of children's books are strewn with casualties, inferior works that will soon perish.
Somewhat rarer is the second type, which is simply the reverse of the first: those who start out writing for children and only later begin to write for an older audience. The obvious worry, that the original genre may constrain the new mode, seems not to apply in this direction. If anything carries over, it is the emphasis on imagination, as in Madeleine L'Engle's books for adult readers. Of course, those who achieve sufficient fame in children's literature, such as Maurice Sendak, will attract adult readers for anything they have written. But the career-arc of Russell Hoban is different; after becoming well known as both an illustrator and writer of children's books, he began to put forth adult novels of astonishing complexity and power. Perhaps accretion is in some ways easier than simplicity.
The third category, what one might term polygraphy, falls somewhere in between the first two types. Though writers such as A. A. Milne, who penned nursery rhymes and box-office hits with equal facility, are hardly a common breed, there has always been a small but recognizable subset of authors who balance an array of diverse projects and have done so since the start of their careers. Louisa May Alcott and C. S. Lewis are two good examples. Their output is generally prolific, yet marked by a high degree of craft. If some critics fault polygraphic authors for lack of depth, this quality may be attributable to speed of composition, or the tendency of popular opinion to equate prolixity with shallowness.
Perhaps the most useful way to illustrate this typology is to examine the career of one writer from each category. In selecting authors for this purpose, I seek a homogeneous group, since the variables of gender, race, class, language, and era introduce complexities that, though intriguing, are beyond the scope of this essay. Accordingly...