Human language is a rich and complex part of human behaviour that can be studied in many ways. The author and his colleagues are developing an application that accepts simple texts as input and presents an animated display of characters acting out the text. It mimics the human visualization of texts, the so-called Theatre of the Mind. In so doing, they need an integrated theory of language; they can test such a theory for consistency and completeness because it is implemented in computable form. In practice, they may have the basis for a useful tool for developing literacy or second-language teaching. By entering expressions, learners can see what the expressions mean and so learn, in a constructive dialogue, some of the language-specific features that they need to master. (Contains 1 note.)