The Ignis Fatuus is a vapor shining without heat.

Tact is the art of making a point without making an enemy.

If I have seen further than others, it is by standing upon the shoulders of giants.

My powers are ordinary. Only my application brings me success.

I have presented principles of philosophy that are not, however, philosophical but strictly mathematical-that is, those on which the study of philosophy can be based. These principles are the laws and conditions of motions and of forces, which especially relate to philosophy.

That one body may act upon another at a distance through a vacuum, without the mediation of any thing else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity, that I believe no man, who has in philosophical matters a compentent faculty of thinking, can ever fall into it.

To any action there is always an opposite and equal reaction; in other words, the actions of two bodies upon each other are always equal and always opposite in direction.