On Motion



On Motion


Typescript of a lecture delivered on February 24, 2023, by Leah Lasell as part of the Formal Lecture Series.

Ms. Lasell describes her lecture: "The new science of motion presented in the last two days of The Two New Sciences is Galileo's last word in a lifelong argument with Aristotle.  Galileo lets us hear echoes of this argument by including the Aristotelian, Simplicio, among his characters.  While Simplicio will argue for the Aristotelian approach tenaciously and with spirit, his understanding is often second hand, rote, and handicapped by his poor mathematical education which consists of nothing beyond book one of Euclid.  Salviati and Sagredo often team up and ridicule the Aristotelian account and tend to just ignore Simplicio altogether whenever the discussion requires mathematical expertise.  It often seems that Galileo is not treating the Aristotelian worldview fairly, as Simplicio himself complains, allowing Salviati to vaunt over an impoverished, dried up, rather rubbish version of Aristotelianism.

In order to better understand the argument between Galileo and Aristotle, we will look at one of Galileo's early unpublished works, De Motu, or On Motion.  Here, Galileo works within the Aristotelian framework, his own outlook a bit like Simplicio's. His goal is not to refute but to improve upon Aristotle by supplementing his account with mathematical reasoning inspired by Archimedes writings on the balance, making Aristotle’s theory more consistent with his experiences of moving bodies.  But as Galileo attempts to bring together Aristotle, Archimedes, and his own experiences of moving bodies, two different and conflicting understandings of nature emerge.

The lecture should be of interest to the whole community: Galileo will lead us through a consideration of Aristotle's philosophy of nature, Archimedes' balance, and Galileo's inclined planes."



Annapolis, MD




A signed permission form has been received stating: "I hereby grant St. John's College permission to: make a recording of my lecture, and retain copies for circulation and archival preservation at the St. John’s College Greenfield Library; make a recording of my lecture available online; make typescript copies of my lecture available for circulation and archival preservation at the St. John’s College Greenfield Library; make a copy of my typescript available online."









Original Format


Page numeration

18 pages