Adam Smith's view that ‘the poets were the first historians’ can be found in many eighteenth-century accounts of the ‘evolution’ of history writing. Prose was generally understood to have succeeded poetry as a higher, more sophisticated form of history writing, emanating from societies that have ‘progressed’ to more complex stages of organization. The historians of commercial, eighteenth-century Britain would, by such logic, write in prose not poetry. While history was understood to be formally evolving towards non-fictional prose, expectations about the effect of history writing on the reader left the distinction between historical and imaginative forms of writing blurred. Eighteenth-century history was expected to stimulate the reader's passions and sympathies as much as any work of fiction. When, in the advertisement to her 1784 poem, Peru, Helen Maria Williams explains that she is not presuming to attempt ‘a full, historical narration of the fall of the Peruvian empire’, only ‘a simple detail of some few incidents that make a part of that romantic story’, she gestures to a tradition of writing which demands narrative flair of its historians:

To write ‘historical poetry’ in the eighteenth century is to evoke an earlier historical moment when poets were the historians. The setting of Williams’ poem is such a historical moment, and its subject is a society at a ‘primitive’ stage of civilization, whose ‘innocent and amiable people, form the most affecting subjects of true pathos’ and who inhabit an exotic climate, ‘totally unlike our own’. The fallen empire of Peru is ripe for ‘poetic description’ (Poems 1786, 2, 54). The narration of the history of the Peruvian empire had recently been undertaken in prose by the French historian Guillaume Thomas Raynal (in his Histoire philosophique des … deux Indes (1770)) and by his Scottish ‘rival’ William Robertson in The History of America (1777). Williams draws on both of these sources in her account of the Spanish colonization of Peru.