The Third Element: Matter

The particles of the 1st Element can fill up the interstices of the 2nd ELement. Among this 1st Element, there are many which get an angular form from the pressure of the 2nd Element globules around them.

These create a 3rd Element of particles, less fit for motion than those of the other two.

• Its particles were formed in the interstices of the 2nd Element*.
• They thus are necessarily smaller than those of the 2nd Element and are urged down towards the center, along with those of the 1st.

In the center, a number of them can take hold of one another. In such a case, they form such spots on the surface of the accumulated particles of the 1st element.

• These are often discovered by telescopes on the face of the Sun

• Those spots are often broken and dispelled, by the violent agitation of the particles of the first element.

Sometimes, however, they encrust the whole surface of that fire which is accumulated in the center.

The communication between the most active and the most inert parts of the vortex is thus interrupted.

The speed of its motion immediately begins to languish. It can no longer defend it from being swallowed up and carried away by the superior violence of some other circular stream.

• In this way, what was once a Sun becomes a Planet.

The sun was the fiery center of a circular stream of aether flowing continually round her.

Thus, the time was when the Moon was a body of the same kind with the Sun.

The moon’s face was crusted over by a congeries of angular particles.

• The motion of this circular stream began to languish and could no longer defend itself from being absorbed by the more violent vortex of the Earth
• The Earth vortex was also a Sun*.
• The moon was chanced to be placed in the Earth’s neighbourhood.

The Moon, therefore, became a Planet, and revolved around the Earth.

In the process of time, the fate of the moon also befell on the Earth. Its face was encrusted by a gross and inactive substance.

The motion of its vortex began to languish, and it was absorbed by the greater vortex of the Sun.

But though the vortex of the Earth had thus become languid, it still had force enough to occasion both the diurnal revolution of the Earth, and the monthly motion of the Moon.

A small circular stream may easily be conceived as flowing around the body of the Earth, at the same time that it is carried along by that great ocean of ether which is continually revolving round the Sun.

In the same way, as in a great whirlpool of water, one may often see several small whirlpools, which revolve round centers of their own, and at the same time are carried round the center of the great one.

Such was the cause of the original formation and consequent motions of the Planetary System.

The Orbits

When a solid body rotates, its center and edge parts complete their revolutions at the same time.

But it is otherwise with the revolutions of a fluid.

The central parts of a fluid complete their revolutions quicker than those at the edge.

The Planets, therefore, were all floating in that immense tide of aether which is continually setting in from west to east around the Sun.

• They complete their revolutions according to their distance from it.

To Descartes, there was no exact proportion observed between:

• the times of their revolutions and
• their distances from the center.

This proportion was discovered by Kepler, but not yet confirmed by Cassini’s observations.

• This was entirely disregarded by Descartes.

According to him, their orbits might not be perfectly circular. It could be longer the one way than the other, and thus approach to an Ellipse.

He thought it was unnecessary to draw this shape with geometrical accuracy or even to describe always precisely the same shape.

This is because Nature can rarely be mathematically exact with the shape of the objects that she produces.

• This is because of the infinite combinations of impulses which must conspire to the production of each of her effects.

No two Planets, no two animals of the same kind, have exactly the same shape, nor is that of any one of them perfectly regular.

It was in vain for astronomers to find that perfect constancy and regularity in the motions of the heavenly bodies, which is to be found in no other parts of nature*.

These motions, like all others, must either slow down or speed up according to the cause which produces them.

• The revolution of the vortex of the Sun either slows down or speeds up.

There are innumerable events which may occasion either the one or the other of those changes.

The greatest difficulty in the Copernican system was the rapid motion of the enormous bodies of the Planets. The Cartesian system tried to solve this.

Descartes taught that to conceive them as floating in an immense ocean of aether.

• Everyone was familiar with the dynamics of water.

The motions of the Heavens was connected with a vast immense system, which joined together a greater number of the most discordant phaenomena of nature, than had been united by any other hypothesis.

It was a system in which the principles of connection, though perhaps equally imaginary, were however more distinct and determinate than any that had been known before.

Descartes’ system attempted to trace to the imagination:

• the order of succession of the movement of the heavenly bodies
• the order of the production of almost all other natural objects

The Cartesian philosophy is now almost universally rejected. The Copernican system is universally received.

Yet, it is not easy to imagine, how much probability and coherence this admired system was long supposed to derive from that exploded hypothesis.

Before Descartes had published his principles, no one really heartily embraced Tycho Brahe’s disjointed and incoherent system.

But it was constantly talked of by all the learned as being probable and on a level with that of Copernicus.

• They took notice of its inferiority with regard to coherence and connection.
• But they expressed hopes, however, that these defects might be remedied by some future improvements.

The philosophy of Descartes gave a complete, and almost perfect coherence on Copernicus’s system.

The system of Tycho Brahe was every day less and less talked of until it was forgotten altogether.

Weakness in the Cartesian System: Lack of Mechanic Details

The system of Descartes connected the real motions of the heavenly bodies according to the system of Copernicus only when considered in the large scale, but not in the small scale.

Descartes never himself observed the Heavens with any particular application.

• He was aware of the observations made before his time.
• But he seems to have paid them no great attention.
• This probably came from his own inexperience in the study of Astronomy.

He was content with observing that perfect uniformity could not be expected in their motions.

He did not solve all the minute irregularities* which Kepler found in the movements of the Planets.

Instead, he showed that irregularities might happen from the nature of the causes which produced them.

• Many successive revolutions lead to other kinds of irregularities.

This relieved him from needing to apply his system onto the observations of Kepler and the other Astronomers.