On Hooke’s Rule of Nature

Lectures de Potentia Restitutiva or Of Spring: Explaining the Power of Springing Bodies (1678) is an important book for the history of science. This book is better known for Hooke's presentation of the law that bears his name. This law, or “Rule of Nature” as the author states, is commonly taught within the context of the analysis of elastic bodies and their deformations. However, the framework in which this law was introduced goes beyond the context in which it is currently taught. Alongside the presentation of Hooke's experiments with springs, the author established his vibratory theory of matter, in which the concepts of congruence and incongruence, initially presented in his Micrographia (1665), would be defined in greater detail. These concepts aimed to theoretically justify the movements of attraction and repulsion in nature. This paper seeks to study the Lectures de Potentia Restitutiva once again to better understand Hooke's thoughts about the rule which bears his name and his conception of gravity, which the author considered a force. Here Hooke's definitions of body and motion will be presented, as well as his actual objective when he formulated the so-called Hooke's Law. As we will see, Hooke intended to create a “philosophical scale” to measure the gravitational attraction between bodies. By considering his previous publications, such as An attempt to prove the motion of the Earth from Observations or Micrographia: or some Physiological Descriptions of Minute Bodies, or even unpublished works such as On the inflection of a direct motion into a curve by supervening Attractive principle, it becomes clear that Hooke was already opening a path toward an understanding of gravity before Newton's Principia (1687) were published. By taking into account the controversy between Isaac Newton and Robert Hooke, we also intend to strengthen the idea that Hooke was an indispensable contributor to the elaboration of a law of universal gravitation. In addition to all this, it will also be argued that the conclusions achieved by Hooke in Of Spring may have also anticipated Newton's third law of motion.