The twentieth century marked a renaissance of interest in Play theory as a locus of study across the disciplines. But Play as a concept remained indistinct and difficult to pinpoint. In 1938 Johan Huizinga published Homo Ludens, the earliest full-length treatise dedicated entirely to a study of Play. Though Huizinga's work may now seem simplistic in comparison to the many studies that have issued from it, a brief look at his study, which is the archetype for many that followed, is a useful starting point. Huizinga's study established criteria for the Play concept and laid the groundwork for a definition of Play to be applied to the social sciences. His criteria for Play are as follows:

1. Play is a voluntary activity.
   
   "Play can be deferred or suspended at any time. It is never imposed by physical necessity or moral duty."
   
   
2. Play is not real.
   
   "Play is not 'ordinary' or 'real' life ... It is an interlude in our daily lives."
   
   
3. Play has its own Time and Space.
   
   "It is limited in time (duration) and limited in space (a field of battle, sports arena or game-board)."
   
   
4. Play is rule-guided.
   
   "It creates order, is order. Into an imperfect world and into the confusion of life it brings a temporary, a limited perfection . . . All play has its rules. They determine what ‘holds’ in the temporary world circumscribed by play."
   
   
5. Play is not serious.

By circumscribing play thus, Huizinga's study of the play element in culture provides a nascent attempt to extend the metaphor of Play into the realm of poetic creation:

The play-mood is one of rapture and enthusiasm, and is sacred or festive in accordance with the occasion. A feeling of exultation and tension accompanies the action, mirth and relaxation follow. Now it can hardly be denied that these qualities are also proper to poetic creation.

Unfortunately, Huizinga's theory is so broad that it is indistinct. Homo Ludens asserts that the institutions of law, prose, perspective, counterpoint, military tactics and even philosophical debate are forms of socially institutionalized game playing. He considers Play to be an essential part of life—going so far as to imply that there cannot be life without games. Yet he does not address the material component in the types of games he studies, nor does he acknowledge the potential ethical component of competition:

Play lies outside the antithesis of wisdom and folly, and equally outside those of truth and falsehood, good and evil. Although it is a non-material activity it has no moral function. The valuations of vice and virtue do not apply here. If, therefore, play cannot be directly referred to the categories of truth or goodness, can it be included perhaps in the realm of the aesthetic? Here our judgment wavers. For although the attribute of beauty does not attach to play as such, play nevertheless tends to assume marked elements of beauty . . . play is a function of the living.

The scope of this model, which incorporates nearly every human behavior into a broad definition of Play, renders Huizinga's study almost useless for an application to a literary-theoretical model. It did, however, spawn other studies more relevant to a theory of Play-Texts.

Metaphorical ambiguity often characterized early Play theories, even in texts of paramount importance. In Philosophical Investigations (1953) Ludwig Wittgenstein is drawn to play and games as metaphors for the human relations established through language. In an effort to accommodate multiple forms of language (language for Wittgenstein is the expressed and interactive communication between people), he proposes that games be defined, not by the features common to them all, but by traits, or resemblances, that link apparently different games together in chains of association. He considers these traits to be like "family resemblances." While members of a family do not look exactly alike, or share all the same features—such as blue eyes or brown hair—each member has some trait that distinguishes him as part of the family.

Consider . . . the proceedings we call games'. I mean board-games, cardgames, ball games, Olympic games, and so on. What is common to them all?—Don't say: "There must be something common or they would not be called ‘games'," but look and see whether there is something common to all, for if you look at them you will not see something that is in common to all, but similarities, relationships, and a whole series of them at that. . . And the result of this examination is: we see a complicated network of similarities overlapping and criss-crossing. [my emphasis]

Such a description may perpetuate indistinct definitions of games and play generally, but Wittgenstein succeeds at constructing a model of expression based on what he terms "language-games." At the heart of Wittgensteinian play is a theory of interactive discourse. Language-games are how we learn new concepts, form social communities and build identities. Therefore, language-games are games of skill played between two or more speakers. As Wittgenstein states, "To understand a sentence means to understand a language. To understand a language means to be a master of technique."

Mastering the technique of language-games requires a skill for "rule-following." Just as there are rules that circumscribe participation in games, there are rules concerning how language functions as a tool of communication in a social context. Wittgenstein's use of play and games as a metaphor for language expression marks a significant moment in the history of Play Theory. When Wittgenstein abandons calculus as a metaphor for logic and language, a metaphor prevalent in his earlier work, he intuitively recognizes the inability of a purely mathematical model to encompass the scope of human communication. Mathematical formulae have rules that are perhaps too strict for Wittgenstein. Formulae are machines that will always render a correct, or incorrect answer. Ethically speaking, in such a model there is a reward or punishment for the ability to conform, or not to conform, to the rules of an equation.

By embracing the game-metaphor, Wittgenstein successfully shifts the notion of rules (inherent to any game) from one of coercion (to find the right equation or answer) to one of willing participation. He does this by asserting that rules are founded on customs of a particular community. He asserts, "The application of the concept 'following a rule' presupposes a custom . . . one follows a rule mechanically . . . without reflecting." According to Wittgenstein, the customs, not words themselves, underlie language. It is the framework essential to our communication, our facility for understanding, and therefore for our being. Though Wittgenstein limits his application of this construct to language and language learning, I believe it equally applies to communities of readers and to the implicit rules of reading and interpreting. In fact, Philosophical Investigations is a vital contribution to a history of Play Theory in the twentieth century.

Another important example is the 1958 publication of Roger Caillois's Les Jeux et les homes [Man, Play and Games] which provides a useful critique of Huizinga, "[Huizinga's] ouvrage n'est pas une étude de jeux, mais une recherche sur la fécondité de 1’esprit de jeu dans le domaine de la culture." [Huizinga’s work is not a study of games, but an investigation into the productivity of the game-spirit in the cultural realm.] Caillois also lends more concrete descriptions of the constituent elements of Huizinga's more metaphorical model. Like Wittgenstein, Caillois extends the study of Play into a potentially moral aesthetic realm. He does not seek the metaphorical application of game playing to larger socio-cultural movements, but seeks to define and classify the types of games that define human Play, He begins by establishing criteria similar to Huizinga’s:

1. Play is Free
2. Play is Separate
3. Play is Uncertain
4. Play is non-Productive
5. Play is Rule-Guided
6. Play is not Reality

Caillois’ study derives its models through an anthropological perspective on Play. He sees games as the artifacts of lost cultures and as indicators of the degree of cultural evolution of existing cultures. He represents schematically four principal categories of games transposed onto two modes of Play (see figure 1). The first mode is ludus, which describes play that requires effort, patience, skill, discipline, perseverance, and gratuitous difficulty. It tempers its counterpart paidia, the uncontrolled fantasy, impulsive exuberance, turbulence, anarchy, spontaneity, and all that is childlike and undisciplined, "la pure dépense d’energie." The categories of games are comprised of pure strategy (agon), pure chance (alea), imitation (mimicry), and exhilaration (ilinx).

What Caillois adds to our model is the claim that each one of the four types of games is accompanied by a distinct psychological attitude: agon is preferred by those who love competition; alea for those who wish to surrender their will entirely to powers outside of themselves (chance, fate, mysticism); mimicry represents the desire to become someone else or to disguise oneself; ilinx is the pursuit of vertigo, which might include anything from chemical addiction to a love of roller-coasters.

Caillois' ideas of Play are central to this discussion of Play-Texts, and I will often draw on his terminology and his Play schema. However, significant modifications of his anthropological model are necessary for an application of these forms of Play to a literary model. First, there are combinations of modes of Play that Caillois considers impossible. For example, paidia, though uncontrolled, is active, and therefore according to Caillois is incompatible with alea, which is a passive surrender to the forces of chance. Nor can ludus the mode of strategy and calculation, coexist with games of ilinx, which involve completely losing oneself in the moment. My analysis diverges significantly from Caillois on this point, as in the texts discussed in this study all modes of play are possible in just about any combination. At Swim-Tuo-Birds, for example, contains elements of ludus and paidia mixed simultaneously with games of agon, alea,mimicry and ilinx.