sidue of the
element of water, whose only obstacle is the air which does not impede
it, is not able to raise itself to a similar altitude? And thou who
didst devise this theory, go and study nature, so that thou mayst cease
to acquire such opinions of which thou hast made so great a collection,
together with the capital and interest which thou dost possess.

[Sidenote: On the Law of Gravity]

80.

The sphere of the earth has gravity which increases in proportion to
the lightness of the element which contains it.

Fire is light in its sphere and its lightness increases in proportion
to the weight of the element which contains it.

{174}

No primary element has gravity or lightness in its own sphere.

81.

The motion made by bodies which possess gravity to the common centre is
not produced by the tendency of the body to find this centre, nor is it
caused by attraction made by the centre, as by a magnet, drawing the
weight towards it.

82.

Why does not the weight remain in its place?

It does not remain because it has no resistance.

And whither will it tend?

It will tend to the centre of the earth.

And why not along other lines?

Because the weight which meets with no resistance will descend by the
shortest way to the lowest depth, and the lowest depth is the centre of
the earth.

And how does a weight find the centre of the earth with such directness?

Because it does not proceed at random, wandering by diverse courses.

[Sidenote: Phenomena governed by Mechanical Laws]

83.

Instrumental science, that is to say, mechanics, is the most noble and
most useful of sciences, inasmuch as by means of it all living bodies
which have movement act; and this movement has {175} its origin in the
centre of gravity which is placed in the middle, dividing unequal
weights, and it has dearth and wealth of muscles and lever also and
counter-lever.

84.

Since these things are far more ancient than letters, it is no wonder
if in our day no records exist to tell how these seas filled so many
countries. But if some record had existed, conflagrations, floods,
wars, changes of tongues and laws have consumed all that is ancient;
sufficient for us is the testimony of objects born in the salt waters
and found again in the high mountains far off from the seas of those
times.

[Sidenote: Heat the Vital Principle]

85.

Heat causes moisture to move, and cold arrests it; as is seen in a cold
count