The orthodox Aristotelians saw pendulum motion as a dynamical anomaly, as 'falling to rest with difficulty.' Thomas Kuhn wrote in his 1962 The Structure of Scientific Revolutions on the impetus theory's novel analysis it was not falling with any dynamical difficulty at all in principle, but was rather falling in repeated and potentially endless cycles of alternating downward gravitationally natural motion and upward gravitationally violent motion. Galileo eventually appealed to pendulum motion to demonstrate that the speed of gravitational free-fall is the same for all unequal weights by virtue of dynamically modelling pendulum motion in this manner as a case of cyclically repeated gravitational free-fall along the horizontal in principle.