Isaac Newton 
Mathematical Principles of Natural Philosophy 

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. The attractive forces of bodies at equal difizances are as the quantities of matter in the bodies; for fince bodies gravitate towards the earth, and the earth again towards bodies with equal moments, the weight of the earth towards every body.