Vortex Movement

by Rene Descartes Icon

2 minutes • 391 words

Table of contents

31. How innumerable diverse motions* may be in the same body
32. How the proper cost of movement, which is also unique in the body, is taken for the sake of many.

31. How innumerable diverse motions* may be in the same body

A body only moves away from bodies which are contiguous and at rest.

If it becomes a part of other bodies having other motions, then it can also participate in those other motions that can be infinitely many.

If someone walking on a ship carries a clock, its wheels will be moved by 4 motions:

The single, proper motion of the clock’s mechanism, as a unit of the clock.

The motion of the man whom it is joined to, and makes up one unit with him.

The motion of the ship fluctuating in the sea, to which the man is joined to and forms a unit of.
By the motion of sea to which the ship is joined to.
By the motion of the Earth to which the sea is joined to.

All these motions will truly be in the wheels of that clock.

But it is not easy to understand or recognize so many motions at once.

This is why we consider each motion of each body only.

32. How the proper cost of movement, which is also unique in the body, is taken for the sake of many.

Every single motion of a body is also made up of multiple motions.

An example is the wheels of carts having 2 different motions:

The circular motion around their axle
The straight motion along the length of the path that they travel

But these motions are not truly distinct.

Each point of the moving body describes only one line.

Nor does it matter that this line is often very curved, and so seems to be generated by many different motions.

This is because we can imagine, in the same way, that any line whatsoever, even a straight line, which is the simplest of all, can arise from infinitely many different motions.

For example, line AB is carried towards CD.

At the same time, point A is carried towards B. Then point A will draw the straight line AD which will depend on 2 straight motions:

From A to B
From A to D

And so, although it is often useful to distinguish a single motion into several parts in this way, for the purpose of easier understanding, yet, speaking absolutely, only one motion is to be counted in each body.