Newton formulated the following concise set of scientific “laws” (which benefited greatly from the physics experiments of Galileo).

Laws of Motion:

1. Unless an object is acted upon by an outside force, the object will stay at rest if already at rest or will continue moving in a straight line at constant speed.

2. The force required to accelerate an object is proportional to its mass.

3. When object X exerts a force on object Y, object Y exerts an equal and opposite force back on X.

Law of Gravity:

That very law which moulds a tear And bids it trickle from its source,— That law preserves the earth a sphere, And guides the planets in their course. - Samuel Rogers, On a Tear

Every object in the Universe is attracted to every other object by a force that is proportional to the product of their masses and inversely proportional to the distance between them.

 

 As simple as these laws appear, he showed how they completely explain Kepler’s Laws for the motions of the planets (requiring a definitely not-so-simple mathematical analysis), and MOREOVER that they account for the motions of all objects we encounter in everyday experience (their interpretation in these terms can lead to huge graduate-level textbooks). These laws remain unchallenged even today in their beautiful simplicity, modified only slightly in extreme conditions by Einstein.