To every action there is always opposed an equal reaction: or, the mutual actions of two bodies upon each other are always equal, and directed to contrary parts.
(The Principia, 1687)

Isaac Newton

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If I have seen further it is by standing on the shoulders of giants.

Isaac Newton (Letter to Robert Hooke, 1676)

We build too many walls and not enough bridges.

Isaac Newton

Plato is my friend, Aristotle is my friend, but my greatest friend is truth.

Isaac Newton (Notes - Certain Philosophical Questions, 1664) 

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