Jan Baptiste van Helmont holds a remarkable place in the history of science and medicine. In many European countries, his work had a strong impact on science and medicine until the early decades of the eighteenth century. His criticism of the Paracelsian tria prima inspired much of Robert Boyle's arguments to be found in the Sceptical Chymist (1661), while his ontological conception of disease contributed to ruling out the ancient pathology as based on humoralism. For long, historians of science have dismissed his work as a farrago of chemical discoveries and fancifulness, while others (mostly historians of chemistry) have isolated his ‘chemical discoveries’ from the rest of his work, crediting him with the identification of gases or with the establishment of chemical atomism. One of the few exceptions was Walter Pagel, whose investigations of Van Helmont's thought, starting in 1930 and culminating in 1982 with his masterly monograph, provided students with a comprehensive account of Van Helmont's medical, chemical and religious views. Despite Pagel and some other scholars’ efforts to show the importance of Van Helmont in the history of science and medicine, most accounts of the ‘Scientific Revolution’ still pay limited attention to Van Helmont.

Georgiana D. Hedesan's aim is to ‘show that Van Helmont sought nothing less than to lay the path to universal knowledge, which in his mind depended on two chief pillars: Christian thought and medical alchemy’ (p. xi). There is no doubt that she has succeeded exceptionally well. Her work is grounded on firm historical and textual foundations, on a thorough study of the whole corpus of Van Helmont's writing, from the early, unpublished, Eisagoge (written around 1607 and confiscated by the ecclesiastical authorities of Malines) to the posthumous Ortus medicinae (1648). The latter was edited and sent to press by his son Franciscus Mercurius on the basis of the manuscript material his father had left. As Hedesan points out, Ortus medicinae is no unitary work: parts of the text included in it were not supposed to be part of the Ortus, and some tracts had been left in a rather chaotic state by Van Helmont.

An Alchemical Quest is divided into two main parts: the first takes into account the influence of alchemy and Paracelsianism, Van Helmont's life and intellectual development, and the structure of the Ortus medicinae. The second focuses on some major themes of Van Helmont's thought: his view of God as the giver of forms and life to creatures, his conception of matter and spirits, the notion of man as image of God, and finally his medical and alchemical pursuits. An Appendix presents a list of chapter-treatises to be found in the Ortus medicinae.

The author pays special attention to investigating Van Helmont's theological views and their sources. She stresses the importance of Christocentrism in Van Helmont's theology, claiming that it provides a unitary view of man and the natural world. Hedesan shows that Van Helmont's theology included a voluntarist understanding of God's relation to the creation: ‘Everything in Nature is in fact moved by the will of God: hence even insensitive beings are pushed towards their own final goals’ (p. 57). She argues, ‘According to Van Helmont, both forms and matter are created by God, and originate ex nihilo. Matter and form are separate in a dualist manner and juxtaposed at a precise moment in the process of generation’ (pp. 60–61). Matter, for Van Helmont, is inert, unless it is activated by spiritual principles, i.e. semina. Van Helmont described forms as perfection, ‘a type of blueprint that is established prior to generation and actualised by the Archeus’ (p. 85). Hedesan addresses the vexata quaestio of Van Helmont's view of water as the ultimate element and the status of the tria prima. Despite his rejection of the three chemical principles, Van Helmont seems to have argued that they were the constituents of water. Hedesan concludes that ‘Van Helmont remains ambiguous in regard to the nature of his tria prima of the water . . . It seems that he thought the behaviour of water betrayed the presence of something akin to the tria prima, but he was not certain that these parts were real’ (p. 103).

The author avoids the pitfall of overemphasizing Helmont's achievements in experimental chemistry. She contends that Van Helmont combined empirical knowledge, notably chemical experiments, with the religious mystical experience. Van Helmont saw his chemical and medical work as a mission. He was convinced that the true understanding of nature could only be achieved through divine intermediation. ‘Like many Paracelsians’, Hedesan writes, ‘Van Helmont firmly believed that knowledge of God is also attainable through direct experience, that is, a mystical comprehension of the self and of God as its Archetype’ (p. 166). The true physicians, for Van Helmont, are made by God, not by the schools, and their goal is to imitate Christ. The Christian medical community is made of physicians who collaborate in order to find cures for the patient. It is apparent that this ideal inspired a number of chemical physicians who in the second half of the seventeenth century advocated medical reform. The present book is based on a meticulous scrutiny of Van Helmont's works and provides the reader with fresh information on the religious and scientific sources of his thought. We have Hedesan to thank for a thought-provoking and informative study that sheds new light on a fascinating, though often misunderstood, character of early modern science.