Modern definition of Motion.
Nor have the modern philosophers, who have endeavoured to throw off the jargon of the schools, and speak intelligibly, much better succeeded in defining simple ideas, whether by explaining their causes, or any otherwise.

The atomists, who define motion to be 'a passage from one place to another,' what do they more than put one synonymous word for another?
For what is PASSAGE other than MOTION?
And if they were asked what passage was, how would they better define it than by motion?
For is it not at least as proper and significant to say, Passage is a motion from one place to another, as to say, Motion is a passage, &c.?
This is to translate, and not to define, when we change two words of the same signification one for another; which, when one is better understood than the other, may serve to discover what idea the unknown stands for; but is very far from a definition, unless we will say every English word in the dictionary is the definition of the Latin word it answers, and that motion is a definition of MOTUS.

Nor will 'the successive application of the parts of the superficies of one body to those of another,' which the Cartesians give us, prove a much better definition of motion, when well examined.
10.

Definitions of Light.
'The act of perspicuous, as far forth as perspicuous,' is another Peripatetic definition of a simple idea; which, though not more absurd than the former of motion, yet betrays its uselessness and insignificancy more plainly; because experience will easily convince any one that it cannot make the meaning of the word LIGHT (which it pretends to define) at all understood by a blind man, but the definition of motion appears not at first sight so useless, because it escapes this way of trial.

For this simple idea, entering by the touch as well as sight, it is impossible to show an example of any one who has no other way to get the idea of motion, but barely by the definition of that name.