The Natural Philosophy of William Gilbert and His Predecessors

Contributions from the Museum of History and Technology: Paper 8
The Natural Philosophy of William Gilbert and His Predecessors W. James King

By W. James King
Until several decades ago, the physical sciences were considered to have had their origins in the 17th century—mechanics beginning with men like Galileo Galilei and magnetism with men like the Elizabethan physician and scientist William Gilbert. Historians of science, however, have traced many of the 17th century's concepts of mechanics back into the Middle Ages. Here, Gilbert's explanation of the loadstone and its powers is compared with explanations to be found in the Middle Ages and earlier. From this comparison it appears that Gilbert can best be understood by considering him not so much a herald of the new science as a modifier of the old. The Author: W. James King is curator of electricity, Museum of History and Technology, in the Smithsonian Institution's United States National Museum.

The nature of a substance is causally prior to its properties; while the definition of the nature is logically prior to these properties. Thus, what we call the theory of a substance is expressed in its definition, and its properties can be deduced from this definition.
The world of St. Thomas is not a static one, but one of the Aristotelian motions of quantity (change of size), of quality (alteration), and of place (locomotion). Another kind of change is that of substance, called generation and corruption, but this is a mutation, occurring instantly, rather than a motion, that requires time. In mutation the essential nature is replaced by a new substantial form.
All these changes are motivated by a causal hierarchy that extends from the First Cause, the Dator Formarum, or Creator, to separate intellectual substances that may be angels or demons, to the celestial bodies that are the generantia of the substantial forms of the elements and finally to the four prime qualities (dry and wet, hot and cold) of the substantial forms. Accidental forms are motivated by the substantial forms through the instrumentality of the four prime qualities, which can only act by material contact.