Referring to my pointing out that the Rambam does not refer to the spheres as solid material, and on the contrary, described them as consisting of something similar to, but not identical to, water…[yet] consisting of a weightless, colorless, unearthly matter (perhaps what we would call some sort of force field?). Rabbi Slifkin, on his blog, wrote:
He also misunderstands the nature of the spheres that Rambam describes, due to his lack of knowledge of Greek philosophy and Ptolemaic astronomy. They are certainly not "force fields"!
Look: Something has to be the cause of the planets’ motions. Either the planets are self-locomotive, or there is an external force that moves them—be it a centrifugal force, a gravitational force, a magnetic force or whatever. The ancients described the force as a belt or sphere pushing the planets as they do; and they described these forces as being non-earthly, ethereal, of elemental water or elemental fire. In our parlance, this would be called a force field, and we differ with the ancients over exactly what the forces are. But if one wants to make the ancient theory look all the more primitive, he will insist that it depicted the universe as consisting of solid, impenetrable spheres. He will make it sound like “crystalline” means not only transparent, but also “made of crystal.”
So why is Rabbi Slifkin so certain that Chazal (not to mention the mesorah) thought that the spheres to which were referring to were impenetrably solid objects? Here is his “solid” proof:
since in the ancient world everyone believed that the sky is solid, there is no question that when each of the Sages received their Torah education from their parents and teachers, they were taught that the rakia is a solid firmament - as were their parents and teachers in turn.
How convincing! (I’m not sure whether this ranks with his proof about what the Sages held about the rakia--from the writings of a 6th century monk.)
But in the little I have learned about what Greek philosophy claimed about spheres, I recall that it is not so clear that it held them to be solids. I would like to quote some sources that shed light on this subject:
Aristotle (384–322 B.C.E.) taught that the ether was a fifth element that carried the stars and planets embedded in it. Plato (428–348 B.C.E.) and the Stoics regarded it as a fluid and the source of life. In antiquity, the substance of the heaven was known as ether, although there was no general agreement on its nature or extent. When Arisototle adopted Eudoxus of Cnidus’s construction to explain the planetary motion, he began a tradition that treated the substance of the heavens as a series of shells surrounding a central earth. He regarded the substance of these shells as a fifth element, distinct from the four terrestrial elements and possessing a natural tendency to move at uniform speed in a circle. The stars and the planets (including the Sun and the Moon) did not move freely. They were merely denser parts of one particular shell, and their motions were the result of the rotation of that shell and the rotation of other shells to which it was attached at its axes. …The ether spheres of both Aristotle and Ptolemy were in immediate contact and excluded vacua. …In contrast to Aristotle’s inanimate but naturally rotating ether, Plato had taught that the heavens were filled with life-giving fire….
--Encyclopedia of the scientific revolution: from Copernicus to Newton, by Wilbur Applebaum, Garland Publishing, Inc. (Taylor & Francis Group), p. 335.
(WILBUR APPLEBAUM is Professor Emeritus, Department of Humanities, Illinois Institute of Technology, where he taught history of science for many years. He has published on various aspects of the Scientific Revolution and on astronomy in the 17th century. He is the editor of the Encyclopedia of the Scientific Revolution .)
So, according to this source, Plato considered the invisible spheres to consist of the element of fire and fluid (reminiscent of אש ומים), whereas his disciple Aristotle (whose astronomical depictions the Rambam generally endorsed) considered it to be ether. Rabbi Slifkin should be aware that ether was not considered an impenetrable solid. It is, in fact, ethereal.
It should be explained, however, that, with both Hipparchus and Ptolemy, the theory of epicycles would appear to have been held rather as a working hypothesis than as a certainty, so far as the actuality of the minor spheres or epicycles is concerned. That is to say, these astronomers probably did not conceive either the epicycles or the greater spheres as constituting actual solid substances. Subsequent generations, however, put this interpretation upon the theory, conceiving the various spheres as actual crystalline bodies.
--A History of Science, by Henry Smith Williams, M.D., LL.D., Vol I, Harper and Brothers, 1904.
To reiterate: According to this source, even considering the spheres “solid crystalline bodies” (yet ethereal?) spheres proposed by Ptolemy was only the invention of later generations. Ptolemy himself “probably” did not conceive them as actual solid substances at all.
At the time of the Greek philosophers…[t]he reality of the spheres was open to debate. Some thought of the spheres as nothing more than mathematical ideas that described motion in the world model, while others began to think of the spheres as real objects made of perfect celestial material. Aristotle, for example, seems to have thought of the spheres as real.
--The Solar System, by Michael A. Seeds, sixth edition, Thomson, Brooks/Cole, 2008, p.56
(Michael A. Seeds wrote Horizons: Exploring the Universe, an astronomy textbook. Currently in its 11th edition, and is used in some colleges as a guide book for astronomy introduction classes. It covers all major ideas in astronomy, from the apparent magnitude scale, to the Cosmic Microwave Background Radiation, to gamma ray bursts.)
In case it seems a bit confusing as to what kind of substance the ancients actually thought the spheres consisted of, Edward Grant, in Planets, Stars and Orbs: The Medieval Cosmos, 1200-1787 (Cambridge University Press, 1996), clarifies for us on page 324,
it is unclear what substance the ancients attributed to the spheres.
(Edward Grant (born April 6, 1926) is Distinguished Professor Emeritus, Department of History and Philosophy of Science, Indiana University, Bloomington. Before arriving at Indiana University in the fall of 1959, Professor Grant taught at the University of Maine and in the history of science program at Harvard University. Professor Grant was twice chair of his department (1973–1979; 1987–1990) where he taught courses on medieval science, natural philosophy and science and religion. Edward Grant was named a Distinguished Professor in 1983. He has received many other honors and awards, including the George Sarton Medal in 1992, the most prestigious award given by the History of Science Society that "recognizes those whose entire careers have been devoted to the field and whose scholarship is exceptional." He has published more than ninety articles and twelve books, including:
· Physical Science in the Middle Ages (1971);
· Much Ado About Nothing: Theories of Space and Vacuum from the Middle Ages to the Scientific Revolution (1981);
· Planets, Stars, & Orbs: The Medieval Cosmos, 1200-1687 (1994);
· The Foundations of Modern Science in the Middle Ages (1996);
· God and Reason in the Middle Ages (2001);
· Science and Religion From Aristotle to Copernicus 400 BC — AD 1550 (2004);
· A History of Natural Philosophy from the Ancient World to the Nineteenth Century (2007).
There is some background to this issue of Rabbi Slifkin insisting that the proposed spheres of ancient astronomers/philosophers were unquestionably solid..
On the Hirhurim blog a few months ago, I had commented on a mention that Rav Yaakov Kaminetzky zt”l observed that when he saw the telecast of Neil Armstrong walking on the moon, it disproved the Rambam’s position that the moon is not a physical body.
I don’t understand how this whole issue arises. The Rambam does not say that the moon is a non-physical body upon which a man could not walk. On the contrary, he contrasts the moon and all the heavenly bodies to angels in the aspect that—unlike angels—they do possess physical form, just as humans do. His only point is that they are not dead and inanimate physical bodies—they are life-forms, with instinctive drives. I fail to grasp Rav Kaminetzky’s kushya on the Rambam.
רמב"ם הלכות יסודי התורה פרק ב הלכה ג
כל מה שברא הקב"ה בעולמו נחלק לשלשה חלקים. מהן ברואים שהן מחוברים מגולם וצורה, והם הווים ונפסדים תמיד--כמו גופות האדם והבהמה והצמחים והמתכות. ומהן ברואים שהן מחוברין מגולם וצורה, אבל אינן משתנין מגוף לגוף ומצורה לצורה כמו הראשונים, אלא צורתן קבועה לעולם בגולמם ואינן משתנין כמו אלו--והם הגלגלים והכוכבים שבהן. ואין גולמם כשאר גולמים ולא צורתם כשאר צורות. ומהן ברואים צורה בלא גולם כלל והם המלאכים שהמלאכים אינם גוף וגויה אלא צורות נפרדות זו מזו:
Everything HaKadosh Baruch Hu created in His world can be divided into three categories. Some are things created composed of material and form, constantly decaying—such as the bodies of man and beast and agricultural produce and metals. And some things are created composed of material and form, but do not change like the former—and these are the heavenly spheres and the stars within them. But the material they are made of is not like the material of the other material things. And some of the things created are form without material at all—and those are the angels. For the angles are not [composed of] body and bulk, but [non-material] forms independent of each other.
Someone else added that the fact space ships went to the moon and further without hitting into or being slowed down by anything shows that there are no spheres. To this I responded,
the Rambam does not say the bodies of the spheres are bodies so solid that they would perceptively slow down rockets or would make an impact on them or vice versa. What he says indicates otherwise:
רמב”ם הלכות יסודי התורה פרק ג הלכה ג
כל הגלגלים אינן לא קלים ולא כבדים ואין להם לא עין אדום ולא עין שחור ולא שאר עינות וזה שאנו רואין אותם כעין התכלת למראית העין בלבד הוא לפי גובה האויר וכן אין להם לא טעם ולא ריח לפי שאין אלו המאורעין מצויין אלא בגופות שלמטה מהן:
They are colorless and tasteless, neither lightweight nor heavy. One might describe them as living forcefields with intuitive motivation
RNS wrote in saying that of course the spheres are solid, since the planets are embedded in them!
Natan Slifkin on September 7, 2010 at 2:50 pm
What do you think the spheres are made of? They are certainly solid, as the stars and planets are embedded within them!
And where do you think that Rambam got the idea of spheres from? It was standard Ptolemaic cosmology. Learn up about it, and you will understand what they thought the spheres are.
He also wrote:
Rambam clearly subscribed to the Aristotelian view that the moon is. And that’s not just a matter of the molecules it is made of; it’s a description of how the whole domain is something else entirely, which material bodies cannot exist in. This quite aside from the question of how we would penetrate the solid crystalline sphere in order to get there! He discusses his view of the cosmos in several places in the Guide, but to understand it, you have to understand the Aristotelian view of the universe.
To this I replied:
A field of force—say, magnetic, or gravitational—need not be impenetrably solid to have some objects “imbedded” in it while allowing others to pass without an impression being made on either. It is true that the Rambam followed the opinion that both the moon and the spheres are made of a fifth element of an ethereal nature unlike anything on our earth. But please point out where the Almagest or other such work writes that whereas the spheres are so solid as to be impenetrable, the moon is so ethereal that it would be impossible for man to walk upon it. Then we can mull over how a solid impenetrable substance in which the gigantic stars are imbedded can be weightless; and then we can try to explain how man’s walking on the moon disproves that it is a living, thinking thing. ..
Despite my prodding (and alluding to information he is lacking or ignoring) Rabbi Slifkin never supplied such a source. Yet he continues to confidently state that it is due to my lack of knowledge of Greek philosophy and Ptolemaic astronomy that I could deny that the Rambam held that the spheres are of solid, impenetrable material.
The sources I cited above indicate that his case is not very solid.