Copiousness as an idea is centrally identified with Erasmus. De copia was a milestone in establishing Erasmus as a humanist scholar after its first publication in Paris in 1512. In turn, this book was a major influence on theories of rhetoric, and of writing in general, throughout the sixteenth century. Following on from Cicero, Erasmus argues that style must be abundant in order to be effective, and that abundance consists of two primary elements: variety of expression and variety of subject matter. Copiousness is the key to writing, or to language, or even to an idea of knowledge. This article analyses the theory of copiousness in Erasmus, and then examines its practical application in the Adagia – another sixteenth-century bestseller – which renders copiousness forth as a physical entity. That work offers the principle of an anthology of all ancient learning, and thus the summation of the bonae litterae. In the process, it provides a model for the problem of how to render the encyclopaedia in literary form.