Subterranean Physics

Subterranean Physics, Book 1, Section 1, Chapter 1.

...[we say], to which we ascribe hyperphysical qualities—namely, those intermediate between spiritual and corporal things—for the purpose of uniting both. Or, to speak more clearly, we attribute the principle and cause of rarity and density to the primordial Heaven; and we establish heaven as the sole and unique matter of the rare and the dense, or of that which can be rarefied and condensed.

N. 5. For we conclude as a certain foundation that all rarity and density proceed from the aforementioned heaven, and not from the air. This is because we call into question—not without basis—all that elastic force which has hitherto been granted to the air. We conclude that even the air itself can neither be rarefied nor condensed without the "spring" Original: "Elaterio"; a term often used in early modern physics to describe the spring-like elastic force or internal pressure of a substance. of heaven, as we will explain more extensively later.

N. 6. Now, whether from postulates or from concessions, we shall meanwhile—with the reader's kind favor—place what we have said so far as foundations and build upon them. Namely, we attribute to heaven the first moving cause of all Motions, whether hyperphysical or physical—specifically of souls, Spirits, and bodies—and finally of everything movable. From what has been said, this consequence cannot be otherwise. For if heaven be the subject of rarity and density, and if all motions are perfected through rarity and density, it follows that the aforementioned heaven is the cause of all motions—as we have said—not only of corporal things, but also of spiritual things. For it is irrefutable that the soul in man moves the limbs by means of the nerves, and moves these through the principles of rarity and density. It is also a common opinion that the operations and actions of spirits occur by means of rarity and density. Indeed, it is most certain that all generations, vegetations, and growths are promoted and completed by these same means. And it could be demonstrated in many ways and by experiments that without rarity and density, all bodies would have to perish: no body could burn or catch fire, and none could increase or decrease. If the pernicious incantations of witches Original: "Sagarum"; referring to female practitioners of magic or sorceresses. were also true, anyone would admit that they could not be performed without the help of rarity and density. Just as no one will deny that the nature of rarity and density is like a hermaphroditic chain The author uses the term "hermaphroditic" to describe a "middle nature" that possesses characteristics of two different things, acting as a bridge between the supernatural and the natural. that connects supernatural things with natural things; without it, neither could Spirits act upon bodies, nor bodies upon Spirits. From all this, it follows that since rarity and density are the most common and primary qualities of bodies, and their origin is attributed to heaven as its proper subject: the aforementioned heaven is the principle of all consequences, from which all

N. 7. motions in bodies are caused, since heaven, as the first place and Element, fills everything contained within it. It now remains for us to explain how heaven is moved in degrees of rarity and density. Therefore, it should be known that heaven, in the state of creation, existed as most dense and most cold. For, as we shall argue elsewhere,

N. 8. rarity is the cause of heat, and density is the cause of cold; nor can dense or cold things be rarefied or become hot except through rare or—what is the same thing—already existing hot things. Therefore, heaven being most dense in the state of creation, it could not be moved or rarefied except either by Angels or by already existing heat. Since the latter was lacking, it was necessary—as we shall demonstrate in the third chapter following—that heaven be moved for the first time in the act of production by Angels, for the sake of rarefaction, whereby it occupied a greater space. Indeed, from excessive rarefaction, as will be taught later, light arose; from whose origin the Angels'