The notion of Tropenliebe in Bernhard Schär’s title has a double meaning. First, it concerns love in the tropics. More in particular, the book focuses on the affectionate relationship between the cousins Paul and Fritz Sarasin, two prominent gentleman-scientists and Asia travellers from late-nineteenth-century Switzerland. The title of the book, however, also refers to the ambivalent love of both gentlemen for the tropics – its ‘original’ nature, its ‘primitive’ people and its intriguing objects. The romantic love between the Sarasins (Schär leaves open whether it carried a sexual component) was taboo circa 1900. The sources that testify to this love are limited and vague. The book therefore mostly focuses on the second type of love to which the title refers, and studies the ways in which scientific fascination for the tropics was entwined with imperial theories and practices.

Schär’s book is not just a double biography. It uses the Sarasin cousins – and particularly their travels to Celebes, the present-day Sulawesi – as a lens to probe into the interactions between science, culture and colonialism. In line with recent transnational and transcolonial trends in historiography, Schär challenges the nation state as the dominant framework for understanding such interactions. The process of colonisation, he stresses, has to be seen as the project of a locally anchored and globally networked bourgeois elite. The Sarasins are thus shown as acting on various stages at once. There is the intellectual context of their Swiss conservative-protestant hometown, Basel; there is the broader context of German-language science; and there is the geographical context of their expeditions in the border region between the expanding Dutch East-Indies and the kingdoms of the Buginese. In this way, Tropenliebe offers a story of unexpected contacts and entanglements. It becomes clear that, while Switzerland did not have its own colonies, Swiss elites actively contributed to and were influenced by the global colonial project.

Schär does not go straight to his main point, but he approaches the subject via various historical detours. The first (lengthy) chapter discusses the bourgeois elites of Basel and the ways in which their economy, culture and science were entwined with overseas activities since at least the eighteenth century. While the Sarasins still largely remain out of the picture, Schär discusses the broader traditions in which their scientific work can be understood. He deals with intercontinental trade and slavery, with collections of African and Asian natural history objects, with networks of missionaries and with the religious convictions that were dominant among Basel naturalists.

After having set the broader scene, the book turns to the politics of the Sarasin expeditions. Schär indicates that the goals of the Sarasin cousins were synergetic with, if not identical to, those of the Dutch colonial rulers and missionaries with whom they shared western bourgeois manners and an imperial worldview. As part of the so-called ‘Ethical Policy’, the Dutch colonial government legitimised territorial expansion as part of a civilisation mission. Alongside missionaries, scientists were also presented as important contributors to such a mission – even if the latter were not of Dutch nationality. The Sarasins could thus rely on support of Dutch colonial rulers and they provided the latter with crucial strategic information. Military conquest eventually followed the same paths as the Swiss scientists had taken on their expeditions. In this way, Schär argues, the Sarasins played a significant role in the changing power relations between the Makassarese-Buginese ruling families and the Dutch imperial power of around 1900.

At the same time, however, the expeditions of the Sarasins had a scientific rationale, which Schär, in line with Pierre Bourdieu, describes as ‘relatively autonomous’. Their scientific interests basically concerned two topics, both of which were inspired by evolutionary theory. First, they hoped to make a contribution to biogeographical discussions that coalesced around the question whether the Asian flora and fauna could be clearly separated from that of Australia. Celebes seemed to offer a promising laboratory to explore this question. Second, the Sarasins had a strong interest in the physical anthropology of Naturvölker, which they saw as vestiges of ‘original’ populations. The presence of ‘Toala’ ethnic groups made Celebes also interesting in this respect. In both their biogeographical and anthropological work the Sarasins were guided by ongoing debates in the English and German language science of their time.

Nevertheless, Schär also makes clear how their work engaged with dynamics that were local to Celebes. He shows the exploitative character of scientific expeditions that could only be carried out with non-western populations in the role of porters, guides and study-objects. Yet, non-western people do not appear in Tropenliebe as passive participants to western knowledge creation. Schär, on the one hand, demonstrates that, occasionally, instances of local resistance against the scientific projects of the Sarasins arose. On the other hand – in one of the most interesting parts of the book – he also indicates how the Sarasins built their knowledge partially on that of Buginese elites, notably the racial classifications of the Sarasin cousins echoed the hierarchical categories in use by local rulers.

In a (short) final chapter, Schär discusses how the imperial science of the Sarasins fed back into the self-understanding of the Swiss. He sketches how parallels were drawn between East-Indian ‘primitives’ and Swiss neolithics, how imperial ideals of civilisation returned in distinctions made between urban elites and ‘Alpine’ rural populations, and how idylls of primitive nature – as conceived in the interior of Celebes – proved inspirational for setting up the Swiss National Park. Switzerland thus appears as a nation created partially through tropical imaginations.

Tropenliebe is theoretically well-informed. Apart from the work of Bourdieu, it takes its inspiration largely from transnational historians such as Frederick Cooper, science and technology scholars like Bruno Latour, and post-colonial theorists such as Edward Said. This leads to an interpretation of science as an instrument of power that is engaged in cross- and transcultural politics. It is a framework that suits the book well, but it also raises some expectations that cannot entirely be met. Through his narrative Schär clearly aspires to give historical agency to non-western populations, but his actual focus (two Swiss explorers) and source material (their personal papers) makes this a very difficult task. His method of detecting traces of non-western knowledge and agency in western sources sometimes leads to original insights – for instance, that western anthropology partially built on local concepts. At other times however, the author (and reader) is frustrated because one can only speculate about the exact actions, ideas and motives of the Toala, Burginese and Makassarese with whom the Sarasins interacted.

The latter should not detract from what is a very original and well-crafted book. Ultimately, it uses the case of the Sarasins for promoting a new conceptualisation of colonialism – one that is equally informed by social history and the history of science. Tropenliebe therefore, will be of interest to a wide variety of audiences. These include historians of transnationalism in Switzerland, historians of science in Germany, historians of colonialism in the Netherlands, and global historians across the world.