Ancient Greek philosophers claimed that the adequate understanding of a particular subject can be achieved only when its nature, or essence, is properly defined. This view furnished the core teachings of late medieval natural philosophers, and was often reaffirmed by early modern philosophers such as Bacon and Descartes. Yet during the second half of the seventeenth century, radical transformation was to take place that led to the emergence of a recognisably modern culture of empirical research. The study unfolded in this book focuses on the works of Robert Boyle, John Locke, and Isaac...