Tractate Berakhot of the Talmud of Eret—-Israel: 0013

1:
This passage is a continuation (and conclusion) of the aggadic passage which was commenced in the previous shiur. This passage, too, is concerned with trying to understand the nature of the celestial heights. This understanding, too, derives from an exposition of various biblical phrases.

2:
Concerning the sky (or firmament) Rav says that on the first day of creation the heavens, as created, were liquid, but on the second day of creation they congealed. Thus, when God says "Let there be a fimament" what this means is "let the liquid harden, congeal, crustify, stretch". This last verb recalls Isaiah 40:22 where the prophet refers to God at creation stretching the heavens "like a tent". This prompts Rabbi Yehudah ben-Pazi to opine that the firmament is like a cloth (which has been stretched taut). He quotes Exodus 29:3, "they hammered out the golden plates", because the verb 'hammer' here derives from the same verbal root as 'firmament' — just as the metal plates were hammered until they were thin so the firmament was made taut and thin. This prompts Rabbi Yehoshu'a to claim that the firmament is only two fingerbreadths thick! If we wish to be pedantic this would suggest a sky which is about four centimetres thick (about 1.5 inches).

3:
Rabbi Ḥanina seeks to outdo Rabbi Yehoshu'a! The sky is less thick than four centimetres. It is like a very thin plate of metal. Job 37:18 reads "Can you help him stretch out the heavens, firm as a mirror of cast metal?" Rabbi Ḥanina interprets this as teaching that the sky is as thin as a plate of hammered metal, but nevertheless very strong and, unlike other thin metals, will never weaken. This idea is developed by both Rabbi Yoḥanan and his colleague and friend Resh Lakish. Their homilies are self-explanatory and need no further explication. Rabbi Azaryah seeks to apply the homily of Resh Lakish to the sky which we see above us today. He says that the story of creation concludes with God completing his work and instituting the Sabbath. Immediately after this the Torah reads "Such is the story of heaven and earth when they were created": even though years have been and gone since then the heavens are still as they were on that first day at the end of creation!

4:
This brings to and end the aggadic exposition of rabbinic cosmology. It also brings to an end the discussion in the Gemara of the first clause of the mishnah. So perhaps we should very briefly recapitulate what we have deduced concerning the recitation of Shema in the evening. Shema should be recited after darkness has set in. This excludes twilight, which is not part of the night time just as the period from dawn until sunrise is not part of the daytime. Twilight lasts for an indeterminate length of time which may roughly be described as starting at visible sunset and continuing for the time it would take a soldier marching at the standard Roman military pace to cover four kilometres. The true indication that darkness has set in is the appearance of a third star in the darkening sky.

Concerning the subject matter of the previous shiur and this present shiur Juan-Carlos Kiel has some pertinent questions:

Is the whole disquisition about the skies, the thickness or density of it, the distances, etc., Halacha? Is an observant Jew requested to believe this? Is the Sefer Hamada, Chapter 3 part of accepted Halacha? Does the Jewish dogma maintain the Heliocentric theory for the Cosmos?

I respond:

Before we began to study the topics covered in these two shiurim I was careful to note that they are "pure aggadata". That is to say that they are not halakhah. The sages, like the scholars of all peoples in all generations, observed what they could see and tried to apply what they could see to an organized cosmology. Clearly, to us today, their cosmology seems ridiculous. But that is because of our advanced scientific knowledge and our greater ability to "see" further into the cosmos. The sages never hesitated to "update" their cosmology when accepted wisdom was seen to be correct. Thus in the passage to which Juan-Carlos refers us in Sefer ha-Mada Rambam offers a different cosmology, based on Aristotelean physics. I have no doubt whatsoever that were Rambam writing the first four chapters of Mishneh Torah today he would have been writing about the 'big bang' and so forth. No one is required to believe either in a geocentric universe or in this cosmology or that cosmology. What is certainly axiomatic in Jewish belief is that "In the begining God created heaven and earth".