Historians of science are alert to the misuse of the word ‘science’ when it is used in most contexts prior to the late nineteenth century. Instead, ‘natural philosophy’ is generally more acceptable when discussing, for example, Newton's work on optics or mechanics. However, both terms seem problematic when applied to medieval writers or to the ancients. In this admirable book Peter Harrison charts the changing conceptions of those activities that we call ‘science’ over a period of two millennia and shows how ‘religion’ also underwent a related series of changes. The domains referred to by these activities are historically contingent, as is their interrelationship (often referred to by the bland phrase ‘science and religion’). The chapters of this book are based on lectures that Harrison delivered in 2011 at the University of Edinburgh in accordance with the will of Adam, Lord Gifford, who instructed lecturers to address ‘Natural Theology, in the widest sense of that term’.

Harrison's main thesis is that for the Greeks the study of nature was a moral activity that aimed to transform and improve the self. This outlook continued with the rise of Christianity, such that there was much overlap between natural philosophy and the Christian religion. The study of the natural world was intended to give people a deeper understanding of their place in the world and thus enable them to lead a moral life. Both natural philosophy and religion changed significantly with the so-called rise of science in the seventeenth century, both natural philosophy and Christian dogma becoming more formalized and expressed in propositional form. Nature was now conceived as obeying physical laws and was no longer a repository for moral laws. Religion was used to support the innovative activities of scientists and in this new partnership natural theology provided the adhesive. The final act occurred in the late nineteenth century with the creation of secular science and thus the separation of science and religion.

Harrison, who held the Andreas Idreos Professorship in Science and Religion at the University of Oxford before moving to the University of Queensland in 2011, is centrally concerned with the issue of how the science–religion relationship should be framed within historical contexts. Thus he argues that the parting of the ways in the late nineteenth century enabled the emergence of the conflict model, as formulated by John William Draper and Andrew Dickson White. They – like many subsequent commentators – conceived science and religion as discrete activities that were essentially unchanged with time. Religion could now be portrayed as an impediment to the development of science and the conflict model was imposed upon earlier centuries, with the Galileo affair as the paradigm example. Opposing this untenable historiography, Harrison advocates the need to understand the different, but by no means conflictual, interrelations of science and religion during earlier periods.

This condensed overview does not do justice to the sophistication of Harrison's arguments and his many insights. So let me focus on a few specific issues, starting with the subject of progress. Harrison reminds us that for Christians the notion of progress originally referred to the moral improvement of the individual, the pilgrim's progress. However, progress subsequently began to lose its religious meaning and no longer referred to the state of the individual's soul. Instead, as trumpeted by Francis Bacon, it became the hallmark of humankind's increasing knowledge of and control over nature. Progress thus became a defining feature of modern science. Yet, as Harrison rightly muses, the modern notion of progress is difficult to sustain as it lacks a clear teleology; it reminds me of the character in Kafka's novella who, asked about his destination, replied ‘I don't know … only away from here, away from here’.

Another major theme is the chronological development from interior to exterior; from self-knowledge to knowledge of the external world. Thus for the Greeks the aim of philosophy was to dispose people to lead a good life and natural philosophy provided exercises in self-transformation. With the spread of Christianity, this moral vision was reformulated in Christian terms but the moral aspect remained since natural philosophy continued to be a way of reflecting on one's place in the world. Natural philosophy thus played a therapeutic role, although Harrison generally avoids engaging with human psychology, which could have entered more explicitly into his analysis.

The creation of secular science in the late nineteenth century also had a significant implication for the role of the scientist. Previously natural philosophy was considered to be a moral and ennobling activity that enabled the practitioner to understand God better through the study of God's creation. In a sense, the natural philosopher pursued a pious calling. By contrast, the modern image of the scientist (though perhaps not the quantum physicist) is of someone who stands outside nature and interrogates it disinterestedly and without considering either religion or moral issues. Ironically, in our own day the ethical problems of science continue to proliferate as science can no longer evoke its religious and moral roots.

One of the limitations of this study is that its principal post-seventeenth-century focus is Protestant Britain, where natural philosophy was often mobilized for anti-Catholic purposes. It is not clear how far Harrison's thesis is applicable, for example, to France or Catholic Spain or even to Protestant Germany, where the notion of Wissenschaft has a broader remit than our ‘science’. Moreover, in equating religion with Christianity from early in the Christian era, Harrison underestimates the historical continuities between Judaism and Christianity.

Although Harrison's book is intended principally as a contribution to the historiography of the relations between science and religion, it should be of value to historians of the early and early modern periods in illuminating how the study of nature was characterized in those periods.