The argument from testimony is not formally a figure of speech. But it is closely related, as we shall see, to several of the figures of speech, and testimonies can themselves contain the whole gamut of schemes and tropes. Like the figures, testimony is extremely widespread in all forms of Renaissance literature. It is most important in the literature of argument: writing, usually in prose, in which an author is arguing in praise or defence of something, or for a particular course of action, or for the truth of an opinion or event. But testimony also appears in poetry and drama; in any genre, in short, in which the resources of Renaissance rhetoric were used to persuade an audience, raise a hearer's passions, or give a reader pleasure.

It is well worth trying to understand the ways in which Renaissance authors used the argument from testimony. Renaissance writing is often governed by conventions derived from formalised arts of argument, of which the art of rhetoric is the most pervasive. To draw attention to these conventions came to be regarded as unskilled and jejune — like a swimmer using a bladder, as one later seventeenth-century image had it. Yet that Renaissance readers were highly conscious of the different forms of logical and rhetorical argument is evident not only from the innumerable handbooks of those arts that formed a staple of the curriculum of the grammar-schools and the early years of a university education, but also from the printed and manuscript analyses that survive of classical, biblical and vernacular literature.