The Aristotelian understanding of motion, as presented by figures like Thomas Aquinas, posited that all motion required a mover, or motor coniunctus, and that motion was a change in place. This view was based on the belief that the natural state of an object was at rest, and any motion required an external cause. In contrast, contemporary scientific understanding, particularly during the "scientific revolution," was marked by Galileo's contributions that challenged these assumptions. Galileo introduced the concept of inertia, which stated that an object in motion would remain in motion unless acted upon by an external force. This was a significant departure from Aristotle's view, as it implied that motion could be sustained without a continuous external cause. Galileo's work laid the groundwork for classical mechanics, emphasizing the role of mathematics in describing and predicting the motion of objects, which was a stark contrast to the more qualitative and metaphysical approach of the Aristotelians.