But it was in his "Attempt to prove the Motion of the Earth" in 1674 that Hooke made some of the most pertinent remarks about gravitation, summed up by three laws: (1) that gravitation exists towards the centres of all bodies, and between all bodies; (2) that all bodies will move in straight lines under their own impulse, but can be disturbed into orbits by other gravitational bodies; (3) that gravity acts more powerfully when bodies are closer together.