The Problem of the Absolute Clock

Abstract

All local movement presupposes a fixed reference point to which the positions of the moving body may be successively related. Just what is this immovable reference point? For Aristotle it is the Earth, because it is contradictory to suppose that the Earth, the center of the circular celestial movements, could be set in motion. This is an error, according to Stephen Tempier and the doctors of Paris; if He wished, God could cause the whole universe, and the Earth at its center, to undergo a movement of translation. William of Ockham then declared that the fixed point to which all local movements are referred is neither the Earth nor any body which actually exists in nature, for all natural bodies are or can be in motion; this reference point is simply an imaginary body. It is a simple concept, added Bonet, a geometrical concept which exists only as esse cognitum within the mind of the mathematician. Thus the whole peripatetic theory of place and motion was overthrown.

From Le système du monde, Hermann, Paris, 1956, VII, pp. 439–441; transl. by David A. and Mary-Alice Sipfle.