From Attractio and Impulsus to Motion of Liberty: Rarefaction and Condensation, Nature and Violence, in Cardano, Francis Bacon, Glisson and Hale

Abstract

There was a particular way of understanding and explaining changes in matter’s quantity whose first exposition can be traced back to the Renaissance in Girolamo Cardano’s classification of the natural motions of the universe, particularly in the motions of impulsus (impenetrability) and attractio (abhorrence of a vacuum). Cardano’s exposition was read attentively by Francis Bacon, whose idea of “motion of liberty” both modified and retained elements of the Cardanian view. The Baconian treatment of the motion of liberty made its way well into the seventeenth century in the works of Francis Glisson and Matthew Hale, who draw heavily on it to provide their own account of rarefaction and condensation. The aim of this essay is to reconstruct the history of the accounts of the processes of rarefaction and condensation held by these authors in order to examine the ramifications of the Cardanian approach in the seventeenth century. This history will not only provide us with new instruments for understanding the intellectual relationship between the Renaissance and the early modern period but also improve our understanding of the transformation of the world picture across the emergence of early modern science.