the spirit. For all the organs of the principal parts serve to perform these three offices; and again all destruction of the organs which causes death brings it to this, that one or more of these fail. Therefore all the rest are but different ways to death that end in these three. But the fabric of the parts is the organ of the spirit, as the spirit is the organ of the reasonable soul, which is incorporeal and divine.

RULE XXXII.

Flame is a momentary, air a permanent substance; the living spirits of animals are of a middle nature between the two.

EXPLANATION.

This matter requires a deeper investigation and a longer explanation than pertains to the present inquiry. In the meantime it should be known that flame is being continually generated and extinguished, so that it is only continued by succession. But air is a permanent body that is not dissolved; for though new air be created out of watery moisture, yet the old air still remains; whence comes that surcharge of the air mentioned in the title concerning the Winds. But the spirit partakes of both natures, both of flame and air; as likewise its nourishers are oil, which is homogeneous to flame, and air, which is homogeneous to water. For the spirit is not nourished by the oily part alone, nor by the watery part alone, but by both together; and though air does not sort well with flame nor oil with water, yet in a mixed body they agree well enough. Likewise the spirit gets from air its easy and delicate impressions and receptions, but from flame its noble and powerful motions and activity. In like manner also the duration of the spirit is a compound thing, not so momentary as flame, nor yet so permanent as air. And it differs the more from the conditions of flame because flame itself is extinguished by accident, namely, by contraries and the hostile bodies that surround it, a condition and necessity whereto the spirit is not subject; and the spirit is repaired from the fresh and lively blood of the small arteries which are inserted into the brain, but this repair takes place according to its own manner, whereof I am not now speaking.

THE

HISTORY OF DENSE AND RARE,

OR

THE THIRD TITLE

IN

NATURAL AND EXPERIMENTAL HISTORY,

FOR THE

FOUNDATION OF PHILOSOPHY:

BEING THE THIRD PART OF THE INSTAURATIO MAGNA.

THE

HISTORY OF DENSE AND RARE,

OR

THE CONTRACTION AND EXPANSION OF MATTER IN SPACE.

INTRODUCTION.

No wonder if nature be in debt to philosophy and the sciences, seeing she has never yet been called on to render an account. For of the quantity of matter, and how it is distributed in bodies (abundantly in some, sparingly in others), no careful and methodical inquiry according to true or approximate calculations has been instituted. One axiom has been rightly received, namely, that nothing is taken from or added to the sum of the universe. And the question, How bodies may be relaxed and contracted more or less without the interposition of vacuum, has been handled by some. But with respect to the natures of Dense and Rare, one has referred them to abundance and paucity of matter; another has laughed at this idea; the majority, following their author, discuss and settle the whole matter by that frigid distinction between act and power. And even those who attribute these things to the proportions of matter (which is the true opinion), and do not maintain the first matter to be entirely deprived of quantity, though indifferent for other forms; yet end the inquiry here, and seek nothing further, without perceiving what follows therefrom; and whereas the matter bears upon an infinity of things, and is as it were the basis of natural philosophy, they either do not touch, or at least do not press it.

In the first place therefore, that which has been well laid down must not be disturbed: namely, that in no transmutation of bodies is there any reduction either from nothing or to nothing, but that it belongs to the same omnipotence to create something out of nothing as to turn something into nothing,