“These and many other considerations are adduced on both sides of this question. Melchior Cornaeus (Ѻ), professor of theology at our own university of Wurzburg, has learned and at some length argued these matters in a discussion of his own dedicated to this topic. On several occasions he and I observed and carefully scrutinized the experiments in question. When I first saw them, I sent an account to Kircher at Rome and to some other friends and scholars, asking their opinion of them. All of them sided with the Aristotelians against the ‘vacuists’. Among the replies I received was this from Kircher.”

— Gaspar Schott (c.1656), summary of communications on Otto Guericke’s vacuum experiments [3]

“I hate seen the account of the experiments sent to my assistant priest and hate read through it carefully. I am astonished by what it going on in the minds of such people that emboldens them to assert that a vacuum has been produced when the very experiments themselves demonstrate abundantly that there isn't a vacuum. The experiments, while they certainly exhibit the presence of great forces, are very far from showing that a vacuum exists and, on the contrary, then can be no better demonstration that a vacuum doesn't exist.

For if a vacuum is produced by this experiment, what, I ask, is the source of the need for such great exertion? It is certainly not the air, for that has all been extracted. Therefore, it must be the ‘nothingness’ that is left behind after the extraction of the air. Can anyone conceive that nothingness can offer a resistance? Has anyone ever heard of such a thing in philosophy?

The philosophical explanation would be that the small amount of air left behind in the opening, creates the resistance because of the supreme impulse it has to fill the vacuum. But as everybody knows, were the continuity of substance to be once ruptured (which, in my opinion, cannot be achieved by any human undertaking) so little air would have neither the potency to fill the space, nor indeed the impulse. The resistance seen and nature's impulse to oppose are better attributed to the rarefaction of air than to anything else. I have seen this kind of thing a hundred times in similar machines. I am in accord with the considerations you bring up and they clearly demonstrate the truth about the non-existence of a vacuum.

I regret that I do not have enough time for a thoroughgoing refutation from first principles of the claims made on behalf of this whole contraption. Therefore, I shall leave the discussion of this issue to your reverence and to Father Cornaeus. Your reverence might be able to do this most opportunely in the Hydraulica when it treats of the vacuum. By the way, my associate, Fr. Valentine Stanfel, sends you his regards. He is also particularly expert in hydrostatics and had decided to publish similar material to that which you are now in the process of doing. As you have anticipated him, he has abandoned his plan. In the meantime, he will not be short of other topics to engage him among the great range of disputed issues. Your reverence should not neglect to correspond with hint; for that would be beneficial to you both.”

— Athanasius Kircher (1656), “Letter to Gaspar Schott”, Feb 26 [3]

Frontispiece from Kircher's Magneticum Naturae Regnum (1667), showing both animate (animals and plants) and inanimate (lodestones) being governed by magnetism (or possibly electromagnetism). [1]

“In contrast to the Cartesian caution, in Germany — where orthodox Cartesianism never gained a foothold — several prominent thinkers embraced the belief that the fixed stars were surrounded by planets and spread throughout an infinite universe. The Ecstatic Celestial Journey (Iter exstaticum coeleste), 1656, by the Jesuit Athanasius Kircher explicitly characterized the fixed stars as suns with encircling planets, although it denied inhabitants even to the planets of our solar system and to the moon. And Otto Guericke, famous for the ‘Magdeburg experiments’ proving the existence of a vacuum, devoted a section of his Experimenta Nova (1672) to an examination and endorsement of Kircher's view of other planetary systems. Von Guericke also noted the possibility of an inhabited moon and planets, and emphasized (following Galileo) that any inhabitants would not be men, but rather diverse creatures beyond all our imaginings. But von Guericke denied Descartes's equation of extension and matter, and instead traced his ideas to Galileo, Kepler, Antonius de Rheita (Ѻ), Mersenne, Bruno, and Nicholas of Cusa.”

— Steven Dick (1984), Plurality of Worlds (pg. 116)

“Nothing is indeed nothing. Nothing is not something; [it is] not this or that or another being, but it is no being. Nothing is nowhere, neither in the mind, nor in the nature of things, nor in the intelligible or sensible world; [it is] not in god, nor beyond god in any creatures. Any whatever being exists; any whatever something exists; all full things have being. Nothing [however] is superfluous; a vacuum is nothing; nothing is empty; nothing is banished from the universe.”

— Athanasius Kircher (1656), Ecstatic Celestial Journey (pg. 434); cited by Edward Grant (1981) in Much Ado About Nothing (pg. 396)

“Nothing is more beautiful than to know all.”

— Athanasius Kircher (c.1670), Publication (Ѻ)