Preface of Principia Mathematica by Newton

# Preface

Pappus tells us that the ancients made a great account of the science of mechanics in investigating natural things. The moderns laid aside the substantial forms and occult qualities and instead have subjected Nature to the laws of mathematics.

The ancients viewed mechanics in two respects:

• rational= this proceeds accurately by demonstration
• practical mechanics= this includes all the manual arts. Mechanics got its name from those arts

But manual workers are not perfectly accurate.

• The most accurate manual workers are the perfect mechanics

Right angles and circles are based on Geometry and are used by mechanics.

• Geometry requires the learner to describe these accurately
• Only then will he solve geometrical problems

Mechanics requires solutions from geometry.

Rational mechanics is the science of motions from forces.

• This part of mechanics was practiced by the ancients in the five powers which relate to the manual arts.

I aim to establish a natural philosophy that relates to gravity, levity, elastic force, the resistance of fluids, and similar forces, as the mathematical principles of philosophy.

The difficulty of philosophy is in investigating the forces of nature, and then from these forces, demonstrate the other phenomena.

• Book 1 and 2 address this.

Book 3 explains the system of the universe which explain the celestial phenomena from the forces of gravity from the sun and the several planets. From there, we extend the principles to explain the motions of the planets, comets, the moon and the sea.

The rest of the natural phenomena can be explained by gravity.

Edmund Halley helped me publish and edit this work.

ISAAC NEWTON

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