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Newton's Third Law of Motion:

From "Philosophiæ Naturalis Principia Mathematica" (Mathematical Principles of Natural Philosophy), first published in 1687 by Sir Isaac Newton:

Law III

"Actioni contrariam semper et æqualem esse reactionem: sive corporum duorum actiones in se mutuo semper esse æquales et in partes contrarias dirigi."

English Translation (from the original Latin):

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

When everyone in the world sees beauty,
Then ugly exists.
When everyone sees good,
Then bad exists.

Therefore:

What is and what is not create each other.

Difficult and easy complement each other.

Tall and short shape each other.

High and low rest on each other.

Voice and tone blend with each other.

First and last follow each other.

So, the sage acts by doing nothing,

Teaches without speaking,

Attends all things without making claim on them,

Works for them without making them dependent,

Demands no honor for his deed.

Because he demands no honor,

He will never be dishonored.

• Tao Te Ching: Chapter 2