The Renaissance and post-Renaissance period marked both the high point and the turning point of alchemy in the West. During the same years in which Kepler, Galileo, Descartes, Boyle, and Newton wrote their revolutionary scientific works, more alchemical texts were published than ever before. But under the impact first of the Reformation and later of the seventeenth-century scientific revolution, alchemy was profoundly changed and ultimately discredited. The organic, qualitative theories of the alchemists were replaced by an atomistic, mechanical model of change, which eventually undermined the alchemical theory of transmutation. The balance between the spiritual and the physical, which had characterized alchemical thought throughout its long history, was shattered, and alchemy was split into two halves, theosophy and the practical laboratory science of chemistry.

The Practice of Alchemy

For the most part Renaissance alchemists accepted the theories and practices of their ancient and medieval predecessors. By...