Allen G. Debus (1926–2009)

These days "magic" seems quite separate from the pursuit of science; Paracelsian iatrochemistry sounds about as scientific as the use of an ouija board. But to divorce these two different kinds practices - the art of magic, the power to conjure, to discern the occult "mathematical secrets of the universe" on the one hand and what we would consider rigorous, empirical observation on the other - is quite ahistorical and misunderstands the spirit of science in the Renaissance. Allen Debus, professor for many years at the University of Chicago and historian of early modern science, drives this point home repeatedly in each of the general area discussed in this book.

The topics covered are ones that you would expect to be found in a book that summarizes the history of major scientific developments from approximately 1400 to 1650 - the study of nature (especially flora and fauna), the increased understanding of human physiology, cosmology, and a brief precis explaining the development of the scientific method generally speaking.

Many of the Renaissance humanists, most notably Paracelsus, wholly rejected the scholasticism and Aristotelianism of previous generations and wished to infuse science and the study of nature with a renewed appreciation for mysticism and alchemy. While a religious understanding of the universe was utterly central to Paracelsian science, he simultaneously emphasized observation, which had been critically ignored by Aristotle and his studious promulgators. (His interest in chemistry, especially iatrochemistry, speaks to his interest in observation.) Aristotle's appreciation of science had been vitiated of all divine wisdom and knowledge by his paganism; Paracelsus wished to correct for this by suffusing science with neo-Platonic, Hermetic, and alchemical texts. He thought that the mathematical formalism of science resembled scholasticism, and he avoided it like the plague.

Empiricism and observation critically improved a number of scientific areas, not just alchemical medicine. In the fifteenth century, crude medieval woodcuts of plants based on Pliny's centuries-old descriptions dominated the scholarship of botany. The drawings of Swiss naturalist Conrad Gesner and Italian botanist Aldrovandi were much more accurate than previous ones, and therefore could greatly benefit both botanists and physicians alike.

In the area of medicine, matters had similarly stagnated. The practices of Galen predominated for a millennium after Galen's death because of their wide use and various translations. Debus discusses the historical developments contributed by those from Vesalius to William Harvey, the first person to accurately characterize blood flow in the human body.

This book is a wonderful introduction for two reasons: it covers the wide range of what were considered the sciences in the few centuries Debus is most concerned with without overwhelming the non-specialist reader, and he continually stresses the continuity between what we would today consider “magic” and empirical, rational, deductive reasoning, or what we would be more likely today to associate with science. He does this effectively in every chapter, and as someone who has a longstanding interest in the history of medieval and Renaissance science, it is refreshing to see an author who isn’t trying to retrospectively make modern science out of something supposedly written by Hermes Trismegistus. He lets the two stand side by side in whatever tension they might have, and deals with them as they are, not as he wants them to be.… (more)