On 4 January 1994 one of the leading Christian historians of science in the world, and one of only two honorary members of the American Scientific Affiliation (ASA), passed away. It was a passing largely unrecognized in the Anglo-Saxon world, a response which was disproportionate to the influence that Dutch professor Reijer Hooykaas’ writing and lecturing activities had on many in the United Kingdom and North America. He repeatedly spoke at conferences of Christians in Science (formerly known as the Research Scientists' Christian Fellowship (RSCF)) in the United Kingdom, including the joint 1985 RSCF/ASA Conference at Oxford University. He also lectured with his close friend Professor Donald MacKay at Regent College. There is a certain irony in the fact that his life and work, and also his Christian witness, were often more recognized and appreciated by foreigners than by his own countrymen.
Hooykaas was trained as a chemist, taught chemistry at two secondary schools from 1930 to 1946 and in 1933 defended a dissertation entitled ‘Het Begrip Element in zijn historisch-wijsgeerige Ontwikkeling’ (The concept element in its historical-philosophical development) at the University of Utrecht. In 1934 at a Free University scientific gathering he gave a clear indication of his interests and concerns in a lecture entitled ‘Natuurwetenschap en Religie in het Licht der Historie’ (Science and religion in the light of history). Both an article on Pascal in 1939 and a lengthy study, Robert Boyle: Een Studie over Natuurwetenschap en Christendom, soon followed.
The history of science had not been a large enterprise in the Netherlands in the 1930s but in 1945 the Free University of Amsterdam appointed Hooykaas to the first chair in the history of science in the Netherlands. All students in the natural sciences and mathematics were required to take his course in the history of science. Students could also select history of science as a minor. Hooykaas had four promovendi one of whom Harry A. M. Snelders became director of the Institute for the History of Science at the University of Utrecht. Hooykaas himself later moved to Utrecht as a professor in 1967 until his retirement in 1976. From 1948 to 1960 Hooykaas taught mineralogy to chemistry students at the Free University and was instrumental in establishing its mineralogy collection.
For many years Hooykaas also played an active role in the Christian Society of Scientists and Physicians in the Netherlands. In 1948 he first lectured at the annual conference of the RSCF in London upon the invitation of Dr. Martyn Lloyd-Jones. As Hooykaas increasingly began to lecture and publish in English his work became more widely recognized and respected. He served as Vice-President for Europe (1967–1976) and then as President of the International Committee on the History of Geological Sciences (1976–1984). In 1970 he presented the Erasmus Lectures at Harvard University and in 1975–1977 the Gifford Lectures at the University of St. Andrews.