Chagigah 11b: One may not explain Maasei Bereishis in front of two students, only one, but the Merkava one may not explain even to one, unless he is wise and understands on his own.

Rambam Yesodei Hatorah 3:9: All the stars and celestial spheres have a soul and mind and understanding, and they are alive and recognize the Creator. Each one according to its level praises and glorifies its Creator as the angels do. And just as they recognize the Holy One, blessed is He, they recognize themselves and the angels that are above them. The stars and spheres’ level of understanding is lower than the angels, but greater than humans.

Rambam Yesodei Hatorah 4:10: What I have said in these Chapters 3 and 4 is called Maasei Bereishis, and the early sages ordered that these matters not be taught in public, only to one person at a time.

חגיגה יא ע”ב:  אין דורשין בעריות בשלשה, ולא במעשה בראשית בשנים, ולא במרכבה ביחיד, אלא אם כן היה חכם ומבין מדעתו.

רמב”ם יסודי התורה פ”ג ה”ט: כל הכוכבים והגלגלים כולן בעלי נפש ודעה והשכל הם, והם חיים ועומדים ומכירין את מי שאמר והיה העולם, כל אחד ואחד לפי גדלו ולפי מעלתו משבחים ומפארים ליוצרם כמו המלאכים, וכשם שמכירין הקב״ה כך מכירין את עצמן ומכירין את המלאכים שלמעלה מהן, ודעת הכוכבים והגלגלים מעוטה מדעת המלאכים וגדולה מדעת בני אדם.

ושם פ”ד ה”י: וביאור כל אלו הדברים שבפרק שלישי ורביעי הוא הנקרא מעשה בראשית, וכך צוו החכמים הראשונים שאין דורשין בדברים האלו ברבים אלא לאדם אחד מודיעין דברים אלו ומלמדין אותן.

Rabbi Yaakov Kamenetsky sought out someone with a television set on Sunday, July 20, 1969 in order to watch astronaut Neil Armstrong land on the moon. He later wrote about this in Emes Leyaakov (Bereishis 1:1) and explained why he held that this historic event proved the Ramban correct and the Rambam incorrect.

The Ramban on the first posuk in Bereishis says that at first, Hashem created from nothing a formless material called hiuli (tohu); then He formed everything from that material. Later, the Ramban clarifies that the heavens were made from one type of hiuli, and the earth was made from a second type. In his comment on posuk 8, the Ramban says, “The heavens mentioned in the first posuk are the upper heavens – not the celestial spheres, but rather above the Merkava. The Torah does not tell us anything about their creation, just as it does not mention the angels, the chayos of the Merkava, or anything that is not physical. It just mentions that the heavens were created from nothing.”

Reb Yaakov said we see from this Ramban that everything in this world – not just the planet earth but all the heavenly bodies too – are included in “haaretz” – since they are all physical. It is only spiritual beings that are the “shomayim” of the first posuk.

“It was these words of the Ramban that stood by me,” he continued, “when we watched people climbing out of the spacecraft down the ladder and onto the moon. And I thought in my heart, what will the Rambam answer now? The Rambam wrote that the moon has a spiritual form. And I thought: now Kabbalah has defeated philosophy. So I took comfort in these words of the Ramban.

“But I could not make peace with the idea that the Rambam erred. If the Rambam could be wrong in Hilchos Yesodei Hatorah, why can’t he be wrong in Hilchos Shabbos and the like?”

He goes on to ask how the Rambam could have written about “Maasei Merkava” in Chapters 1 and 2, and “Maasei Bereishis” in Chapters 3 and 4, if Chazal say (and the Rambam quotes it himself) that one may not teach these matters in public. His answer is that the source for the ideas in these four chapters is not the Torah, but the Rambam’s own philosophy. When he was shown later by Rabbi Yitzchak Perman that Rabbi David Arama writes similarly in his commentary on the Rambam, Reb Yaakov exclaimed שישו בני מעי (echoing R’ Elazar’s joy at finding out that his legal decisions were correct – Bava Metzia 83b).

Source: Emes Leyaakov p. 15; Making of a Godol p. 157

[There are a number of questions about this story:

1. Reb Yaakov assumes that when the Rambam wrote that “all the stars and celestial spheres have a soul and mind,” he meant that the moon is not a physical ball of rock, and thus it would be impossible to walk on it. But what is the indication that the Rambam meant that? Maybe he meant the moon is physical but it has a soul and mind – just like a person is physical yet has a soul and mind.
2. Even if the Rambam’s scientific statements were disproven, why would that mean that “kabbalah defeated philosophy” (where philosophy has the broad connotation it had in the ancient world, which included science)? It would only be the Rambam’s particular version of astronomy that was disproven.
3. Reb Yaakov asks a very good question about how the Rambam wrote about matters that Chazal forbade to teach. How does Reb Yaakov’s answer – that the Rambam did not get his information from Chazal – resolve this question? If the Rambam indeed held that Merkava means philosophical analysis of G-d’s attributes, and Bereishis means astronomy, then he was teaching what is forbidden to teach.

On this last point, I think the answer lies in Yesodei Hatorah 2:2: “What is the way to reach love and fear of Hashem? When one meditates on His amazing and great actions and creations, and sees from them His boundless wisdom, immediately he loves and praises Hashem and has a great desire to know Him, as Dovid said, ‘My soul thirsts for G-d, for the living G-d.’ And when he thinks of these things, immediately he falls backward and feels fear, knowing that he is a but a small, insignificant creature, with tiny knowledge, standing before the Perfect Mind. As Dovid said, ‘When I see Your heavens… what is man that You are mindful of him?’ And based on these words, I will explain general principles about the work of the Master of the Universe, so that they might be a starting point for a wise person to love Hashem.”

We see here that the Rambam does not start down this road with the goal of teaching Maasei Merkava and Maasei Bereishis. He is only outlining a few general points to inspire fear and love of Hashem. The prohibition is only violated when one teaches it in detail.

Similarly, in 2:11-12 he writes, “These things that we have stated in these two chapters are like a drop in the ocean of what should be explained in the subject. And the explanation of all the principles in these two chapters is what is called Maasei Merkava. The earlier Sages commanded not to expound these matters to more than one person, provided that he is wise and can understand on his own. Then one can tell him the beginnings of the subjects (ראשי הפרקים) and a bit (שמץ) of the matter, and he understands on his own and knows the end of the matter and its depth.

There is clearly a difference between “a drop in the ocean” – which is allowed to state publicly – and “a bit” – which is forbidden.

Similarly, in 4:10 he says, “All these things that we have spoken on this subject are like a drop in the bucket, and they are deep matters. And the explanation of all these matters of chapters 3 and 4 is what is called Maasei Bereishis.” 

A “drop in the bucket” is allowed to state publicly; “the explanation of all these matters” is not.

But if we say this, we no longer need Reb Yaakov’s answer, that the Rambam’s source was not the Torah or Chazal. Even if his source were the Torah, since he only gave us a drop in the ocean, it would be permitted. So what did Reb Yaakov’s answer accomplish as far that question?

It does, however, explain how the Rambam could have been wrong about the moon. I don’t have access to the commentary of Rabbi David Arama, but the anonymous commentary on the side of Yesodei Hatorah 2:1-2 writes, “These rules that the Gaon (the Rambam) states – some of them are apparent to the eye, and some of them can be proven using science and mathematics. Therefore we believe the words of the Gaon z”l, who knew these matters through proofs. And whoever wishes to know the proofs to his words should go and study the branches of wisdom, until he knows the creations of Hashem well.” This seems to support Reb Yaakov’s contention that the Rambam’s source was not Chazal.]