Kepler's laws of planetary motion planets. However, Newton states in his Principia that he considers forces from a mathematical point of view, not a physical, thereby taking an instrumentalist view. Moreover, he does not assign a cause to gravity. Newton defined the force acting on a planet to be the product of its mass and the acceleration (see Newton's laws of motion). So: The Sun plays an unsymmetrical part, which is unjustified. So he assumed, in Newton's law of universal gravitation: As the planets have small masses compared to that of the Sun, the orbits conform approximately to Kepler's laws. Newton's model improves upon Kepler's
Valerio-Horatian Laws on the plebiscites, there were three instances of such law. There were two other laws on appeal which were proposed by two consuls who were also members of the Valeria family, one by Publius Valerius Publicola in 509 BC and one by Marcus Valerius Corvus in 300 BC. Two other laws which provided for the plebiscites to be binding on the whole people were also proposed, one by Quintus Publilius Philo in 339 BC and one by Quintus Hortensius in 287 BC. This has led some historians to argue that in both cases the first and second laws are unhistorical