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.

For some time now scholars have debated why Thomas Hobbes was never made a Fellow of the Royal Society. But about his relations with a different learned institution – Oxford University – there has been little doubt. Hobbes had been a student at Magdalene Hall between 1602 and 1608, but thereafter he was (one brief attempt at rapprochement aside) one of Oxford's most inveterate enemies, and indeed an enemy of existing universities altogether. Few of the very many controversial things he said in Leviathan (1651) aroused more immediate anger than his closing claim that the book might be ‘profitably taught in the Universities’. Hobbes's early readers reacted to this statement, as Hobbes himself subsequently acknowledged, with incredulity and disgust. Moreover, when members of the English universities were accused of professing Hobbes's ideas, as Daniel Scargill was at Cambridge in 1668, they were liable to find themselves in serious trouble.

Yet, despite Hobbes's hostility to them, the universities have a significant place in all of his major writings. They were a consistent component of his systematic political philosophy between the Elements of Law of 1640 and the Latin Leviathan of 1668. Hobbes regarded the universities as having a necessary ‘office in a Common-wealth’, and held that it was a duty of the sovereign representative to oversee what they taught. He was also, however, bitterly critical of the political role the universities had played in the Civil Wars, and also critical more generally of the philosophy they taught.

Questions of proof and persuasion are important in the history of the sciences of any period, but they are particularly pressing in the case of early modern Europe. The sixteenth and seventeenth centuries saw more self-conscious theoretical reflection on how to discover and confirm the truths of nature than any period before or since; the same period also manifested a huge range of practical strategies by which investigators of the natural world set about demonstrating their findings and convincing their audiences of their claims. Studying these strategies of proof and persuasion has opened up vistas of opportunity for historians of the sciences in early modern Europe. In a range of disciplines, from the social history of medicine to the history of philosophy, historians of the period have argued for the ineradicable significance of forms of proof and persuasion in understanding their various objects of inquiry. The rhetorical form of texts and even objects has come to be seen as constitutive of their meaning, not separable from it. Furthermore, an increasing number of studies have shown how early modern physicians, mathematical practitioners, and natural philosophers all exploited the different and historically specific resources of proof and persuasion that they had at their disposal.

The study of proof and persuasion provides a further opportunity to the historian: It offers a means of bridging the gap between a text (or a practice) and its reception. As the reception, rather than the genesis, of developments in the sciences has become an increasingly important aspect of historiography, it has also become increasingly apparent that this reception history is often extremely difficult to reconstruct.