When questions of this sort are asked of me, my safest answer would appear to be as follows: Some one says to me, 'O Stranger, are all things at rest and nothing in motion, or is the exact opposite of this true, or are some things in motion and others at rest ?' To this I shall reply that some things are in motion and others at rest.

'And do not things which move move in a place, and are not the things which are at rest at rest in a place ?' Certainly.

'And some move or rest in one place and some in more places than one ?' You mean to say, we shall rejoin, that those things which rest at the centre move in one place, just as the circumference goes round of globes which are said to be at rest?
'Yes.' And we observe that, in the revolution, the motion which carries round the larger and the lesser circle at the same time is proportionally distributed to greater and smaller, and is greater and smaller in a certain proportion.

Here is a wonder which might be thought an impossibility, that the same motion should impart swiftness and slowness in due proportion to larger and lesser circles.

'Very true.' And when you speak of bodies moving in many places, you seem to me to mean those which move from one place to another, and sometimes have one centre of motion and sometimes more than one because they turn upon their axis; and whenever they meet anything, if it be stationary, they are divided by it; but if they get in the midst between bodies which are approaching and moving towards the same spot from opposite directions, they unite with them.