Galileo Verus Aristotle
Table of Contents
We are in a boundless sea from which there is no getting out, ever.
This is navigating without compass, stars, oars, or rudder, in which we must either:
- pass from bank to bank or run aground, or
- sail forever lost
We wuill resolve earth’s stability as explained by Aristotle, Ptolemy, and others and prove that the Earth moves circularly.
Only circular motion or rest can lead to the optimum placement and perfect order of the parts of the universe as to their local situation.
Let us now consider the whole terrestrial globe. What can happen to make it and the other world bodies keep themselves in the natural and best disposition?
It is either:
- at rest and remains perpetually immovable in its place, or
- it stays always in its place but revolves itself or
- it goes about a center, moving along the circumference of a circle
Of these, Aristotle and Ptolemy and all their followers say that it is the first which has always been observed.
So how can something not moving create a downward motion?
Nature uses straight line to restore particles of earth, water, air, fire, and every other integral mundane body to their whole when any of them are separated and transported into some improper place.
- This is unless it can be restored by finding some more appropriate circular motion.
I think that this original position is better than to attribute straight motion as an intrinsic and natural principle of the elements.
The Peripatetic believes that:
- celestial bodies are incorruptible and eternal
- the terrestrial globe is corruptible and mortal
- but there will not come a time when, the sun and moon and other stars continuing their existence and their operations, the earth will be annihilated along with the rest of the elements
Therefore generation and corruption belong to the very small and superficial parts, and not to the whole.
Aristotle argues generation and corruption from the contrariety of straight motions.
So let us grant such motions to the parts, which alone change and decay.
But the whole globe and sphere of the elements will have either circular motion or perpetual rest.
What is thus said of earth may be said as reasonably of fire and of the greater part of the air, to which elements
The Peripatetics are forced to:
- assign an intrinsic and natural motion
- abolish from nature that motion with which they move, have moved, and are to be moved perpetually.
This is because they assign an upward motion to air and fire.
- This is a motion that never belongs to the said elements, but only to some of their particles
- This only happens to restore them to perfect arrangement when they are out of their natural places
On the other hand, they call circular motion (with which they are incessantly moved) preternatural to them, forgetting what Aristotle has said many times, that nothing violent can last very long.
To all these things we have the most suitable answers, which I omit for the present in order that we may come to the particular reasons and sensible experiments which should be finally preferred, as Aristotle well says, above anything that can be supplied by human argument.
So which of 2 general arguments has the more probability?
- Aristotle writes that sublunar bodies are by nature generable and corruptible, etc.
Therefore they are very different in essence from celestial bodies, these being invariant, ingenerable, incorruptible, etc. This argument is deduced from differences of simple motions.
- Salviati assumes the integral parts of the world to be disposed in the best order, and as a necessary consequence excludes straight motions for simple natural bodies as being of no use in nature.
He takes the earth to be another of the celestial bodies, endowed with all the prerogatives that belong to them.
The latter reasoning suits me better up to this point than the other.
Therefore let Simplicio be good enough to produce all the specific arguments, experiments, and observations, both physical and astronomical, by which one may be fully persuaded that the earth differs from the celestial bodies, is immovable, and is located in the center of the universe, or anything else that would exclude the earth from being movable like a planet such as Jupiter, or the moon, etc.
