This book is a translation of Mauricio Nieto's Las máquinas del imperio y el reino de Dios: reflexiones sobre ciencia, tecnología y religión en el Atlántico del siglo XVI (Bogota 2013). Nieto is interested in ‘understanding the relations between knowledge, technology, religion, and empire’ (p. 295) as well as understanding ‘European rule’ (p. 22) over the world. He offers ‘a careful study of the techno-scientific practices that allowed for both the European appropriation of the New World and the building of a new world order’ (p. 26). Nieto argues that the ‘triumph of Christians in a large part of the world is explained by the mobilization and combination’ of ‘agents that are both social – human – and technical, natural, or even divine’ (p. 29). Nieto offers a synthesis of recent work on the Iberian empire and science history and recasts the narrative in terms of human and non-human associations.

Nieto argues, first, that in the context of the Iberian long-distance empires, new rules emerged ‘for the production of knowledge’, such as ‘the establishment of norms for the organization of information, the definition of common frames of reference, the standardization of data and authoritative measurements, and the classification of experiences’ (p. 73). These rules then produce scientific practices that were fundamental in the establishment of the Iberian empires (p. 23). Second, and connected to this argument, he argues that these scientific practices emerged from a European act of ‘comprehension’ as ‘an act of appropriation, a process of translating the unknown into something familiar, of incorporation and domestication, as well as a recognition of the alien’ (p. 24). He adds quickly that in this act of comprehension, ‘agents and objects of appropriation are constructed’ simultaneously (p. 24). ‘From this point of view, 1492 is a date that should recall the “discovery” or “construction” of both America and Europe’ (p. 24). I am sceptical of this second argument but I agree with the significant idea that empires and knowledge constitute each other.

Nieto's book is organised into seven chapters. Chapter i provides an overview of the Portuguese and Castilian exploration projects and discusses the winds and currents that shaped them. Chapter ii discusses the creation and institutionalisation of the Casa de la Contratacion and the Consejo de Indias – the House of Trade and the Royal Council of Indies – and their roles in the emergence and consolidation of Castille's far-flung American empire and knowledge-producing practices. Chapter iii discusses sixteenth-century manuals of navigation and cosmography written in Castile and Mexico. Chapter iv studies nautical knowledge, ships, instruments, pilots and sailors, as leading actors in this story of domination and control. Chapter v focuses on maps – as artefacts representing ‘Europe's power over the New World’ (p. 34). Chapter vi delves into the natural history of America and issues of classification and description. In the final chapter Nieto goes back to the ‘book's central questions about the role of Iberian science in the history of modern Europe’ (p. 34).

Nieto's book accomplishes at least three tasks. First, it ‘sums up the work of’ (p. 34) a group of scholars based in the USA and Spain working on the history of the Iberian empires and the history of science. This welcome synthesis connects the Iberian empire and the history of science, a rich and creative area of research. Nieto does superb work in analysing their connections. Second, Nieto frames the Iberian history of empire and knowledge production as histories that emerge from the heterogeneous association of humans and non-human actors. He follows the actor-network theory's insight that humans and non-humans constitute associations of heterogeneous actors or collective hybrids, which are integral to understanding the past. Nieto suggests that ‘phrased in a different way, similar ideas were found in sixteenth-century writings on navigation’ (p. 187) – perhaps sharing the argument that we have never been modern. Nieto's work is a welcome approach to rethinking the histories of science, empires and Iberia with the insight that humans and non-humans constitute associations of actors integral to history. He does an excellent job of incorporating these heterogeneous actors into his narrative. Third, although Nieto is ‘not interested in either celebrating not denying Eurocentrism’ (p. 22), he is trying to understand ‘European rule’ ‘over the whole world’ (pp. 22, 26). I found this aspect of his book less convincing.

Nieto explains that his project's ‘point is precisely to learn about the great Christian endeavor of conquering the whole world’ (p. 26). I question this way of framing the project. The world was mostly a world of empires in the sixteenth and seventeenth centuries. Euro-Christians managed to carve spaces for their imperial and commercial activities through violence and alliances, as did the Ming, Mughal, Safavid, Russian and Ottoman empires, among others, in their areas of influence and expansion. In Africa and Asia the limited sixteenth-century Ibero-Christian empires at most carved a space for their fortresses and commercial activities. These areas became sites for the circulation of people, practices, technologies, things, plants and animals. Thus, in 1521, when the Portuguese attacked the port of Guangzhou (in Ming territory) with cannons, they managed to destroy but not control the port. A year later, when they returned, Guangzhou authorities were ready with their own cannons and managed to destroy the Portuguese ships. In America, Castilians, pathogens and indigenous allies toppled the Triple Alliance in Mexico (1521) and the Inca empire (1532) in the Andes; surviving local elites and Christian authorities negotiated new imperial configurations of domination. Yet most of the Western hemisphere was still outside Christian control: Mayas, Chichimecas, Pijaos and Mapuches, among many other indigenous groups, controlled their territories and fought Christians throughout the sixteenth century and beyond – a history of resistance that is still unfolding today. Even in early modern areas of Christian control, Christians faced constant resistance and the creation of new cultures through processes of transculturation. Caribbean black practitioners, for instance, created an empirical culture similar to the European one Nieto explores in his book, from indigenous, European and African ideas and practices circulating in the region. Technologies and knowledges emerged, circulated, changed, adapted, disappeared and moved to the margins in this early modern world of empires.

Nieto has written a critical book connecting the histories of science, the Iberian empires, knowledge production and human and non-human associations. As he argues, ‘The Iberian endeavor to catalog, name, and describe the nature and geography of the New World was a colossal one, and the results were remarkable: ethnographic treatises, complex legal and moral debates, encyclopedias of natural history, treatises on medicinal botany, maps, and navigation manuals’ (p. 302). Nieto's book helps us understand the Iberian empires as entangled political, commercial and scientific endeavours (p. 304); and to situate sixteenth-century Iberian science as a significant episode in the history of science.