Monday, September 6, 2010

Without Doubting Chazal for a Second

Sent: Monday, September 06, 2010 5:37 AM
Subject: Chazal and science

Dear Rabbi!

I'm having difficulty with a passage the gemara (Zevachim 22) quotes from a braita, stating that if the eye of a large fish were to dissolve and pool in its socket; one would be able to immerse himself in it as if it were a mikva, provided it has the 40 saah required for a mikva. And this is codified as law in Rambam and Y"D (201.33).

Without doubting chazal for a second, can this be explained or reconciled with modern science?
From what I recall the largest eye ball is that of a horse and or a squid (while the large fish whose primary senses are scent and sound have relatively small eyes) Which is still drop in the bucket from the 25-35 cubic feet of volume required for 40 saah.

Any information or guidance would be greatly appreciated.


A fascinating question! Without doubting Chazal for a second, this cannot be explained or reconciled with modern science. However, while the Rishonim of Ashkenaz and many Acharonim would not doubt Chazal for a second, this is not true of the Rishonim of Sefarad and many other Acharonim, such as Rav Hirsch. They would take the approach that Chazal were simply adopting prevalent beliefs of the period in considering that such creatures may exist. A friend of mine has put together a comprehensive list of such opinions at

Best wishes,
Natan Slifkin


  1. What's the problem?

    Assuming that the citation is correct [I didn't check the gemara], the case is a theoretical one. The gemera doesn't say that there is such a fish, merely that if there would be, what would be it's status?

    Extreme cases are hardly uncommon in the Gemara, and while one might want to say that the Gemara would not discuss cases that don't exist, it is obvious from other places that the style of the Gemara is often to consider "forced" cases (certainly those that are unlikely, presumably those that are impossible as well) to clarify a din.

    Even if one prefers to follow the assumptions (mesora?) of those Rishonim who do not accept the presence of errors in the Gemara, this citation appears to present no problems.

  2. "this citation appears to present no problems."

    This is not true. Even when the Talmud presents hypothetical or absurd cases in order to learn distinctions, the cases are in the realm of unlikely but not impossible. Clearly in the context of the discussion in the text the rabbis thought such a thing possible.

  3. Yeah, bizzare example chosen.

    Why not the one about the flying camel?

  4. I was formulating a response to R' Slifkin's post, but Mikeage seemed to be reading my mind, and worded it more eloquently than I would've.

    I guess the question is, what did the -Rishonim of Sefarad and many other Acharonim, such as Rav Hirsch- say about extreme hypothetical cases?

  5. The largest eyeball known is that of the collosal squid,
    at about 27cm (=~11 inches) across. Volume of a sphere = (4/3)(PI)(r^3).

    This is still not 25-35 cubic feet.

    *Maybe* there is a still unknown, much larger fish.

    In Bava Batra 74a:
    R. Johanan related: Once we were travelling on board a ship and we saw a fish that raised its head out of the sea. Its eyes were like two moons, and water streamed from its two nostrils as [from] the two rivers of Sura.

    In Bava Batra 73b:
    Rabbah b. Bar Hana further stated: Once we were travelling on board a ship and saw a fish in whose nostrils a parasite11 had entered.12 Thereupon, the water cast up the fish and threw it upon the shore. Sixty towns were destroyed thereby, sixty towns ate therefrom, and sixty towns salted [the remnants] thereof, and from one of its eyeballs three hundred kegs of oil were filled.

    But we can wonder whether this was meant literally or allegorically.

    However, we could also simply say that Chazal are right and Rashi is wrong. Rashi says that it is the eye, once it dissolves. But previously, in context, we said:

    אלא למעוטי יבחושין אדומין אפילו בעינייהו

    Note the word בעינייהו. Now, in the statement of מטבילין בעינו של דג, note the word בעינו.

    I don't know that this is right, and it may well be forced. I am just tossing out a few ideas.


  6. R' Steinsaltz (and others) have pointed out that for many years, people thought the Gemara's discussions of "flying towers" and transferring embryos were theoretical (and they either were, or based on faulty science). Then science accomplished these things, and their rulings came in handy.

    I have no idea how this one would. Maybe we'll find some giant alien fish, although why we'd have to make use of its eye socket is beyond me.

    Don't be too troubled by the codes including it: They include lots of lines, verbatim, from the Gemara. My favorite is the list of books of Tanach, copied exactly from Bava Batra to the Rambam, Tur, and Shulchan Aruch, and followed by no one today.

  7. From Sacred Monster:

    Rabbi Yitzchak of Vienna (1180-1250) notes that the Talmud is full of (legitimate) discussions of cases that do not exist. He lists the case of the two-headed person as an example, as well as other mutants discussed in the Talmud, such as animals born in the form of humans. Rabbi Yitzchak raises this point in the context of his explaining one passage in the Talmud as referring to the usage of an animal as a cover for a coffin. Such a case is absurdly improbable; but Rabbi Yitzchak states that this does not preclude the possibility of the Talmud discussing such a thing. The same approach is found in Tosafos: "…But is it normal to make a cover for a coffin out of an animal?! The answer is that even though it is not normal to do so, we nevertheless find many unlikely cases that the Talmud discusses, in order to analyze them and be rewarded for this." (Tosafos to Kesuvos 4b, s.v. Ad Sheyistam)

    However I think that in this case of the fish-eye, the context indicates that they did believe it to exist. And Rambam probably wouldn't have put it in the Mishneh Torah otherwise.

  8. "However I think that in this case of the fish-eye, the context indicates that they did believe it to exist. And Rambam probably wouldn't have put it in the Mishneh Torah otherwise."

    Why do you believe that? And why if there is a fish of that size, would you need it to make a mikveh? If you have a fish, you have water, and don't need the fish eye.

    Also, how large was the eye of the Pliosaur?

    I think the important lesson from this gemorah, is that if you can't truck in snow, or don't have rain, you can just collect fisheyes and use those.

  9. my spin on this, expanded.

    basically, i argue that בעינו doesn't mean the fish's eyeball, but the actual substance of the fish.


  10. Rabbi Slifkin,

    I love the first two sentences of your answer.

  11. indeed, it was an excellent turn of phrase.


  12. i think many are missing the point - it should be understood - that if such a fish existed than the eye socket would qualify as a mikva as Rabbis Slifkin's first paragraph of answer dated September 6, 2010 1:55 PM implies

  13. Lets get technical:
    d = 11 inches = 0.916666667 feet
    r = d/2 = 0.4583 feet
    Volume = (4/3)pi r^3
    Volume = 0.4033 ft^3
    This is a far cry from 25 ft^3!

    How big an eye would we need??
    WE want 25 cubic feet:
    25 = (4/3)*pi*r^3
    r^3 = 25/((4/3)*pi) = 5.968 feet^3
    r = 1.8139 feet = 21.767 inches
    d = 2r = 43.5340 inches

    So they have found a squid with an 11 inch diameter eye, where as per the gemara you would need a fish with a 43 inch-wide eye.

    From wikipedia:
    "The Atlantic Giant Squid has the largest recorded eyes of any animal with an approximate diameter of 50 centimetres (20 inches),[6] although those of the Colossal Squid are thought to reach an even greater size."

    So now we are up to 20 inches across, with "Colossal Squid are thought to reach an even greater size". How much bigger??

    From another news site:
    "Giant squid, the world's largest invertebrates, are thought to reach sizes up to 60 feet (18 meters), but because they live at such great ocean depths they have never been studied in the wild. "

    Now we have no idea how big they can get because we have only ever seen one adult alive! see

    Always good to keep an open mind....

  14. To Nachum:

    I'm afraid I didn't understand a word of what you said in your third paragraph, but I am very interested in what you have to say. (First two paragraphs were very interesting). Please explain.

  15. Actually, the minimum shiur of a mikva is 3 cubic amot. Taking 50 cm as a reasonable measure of an ama, that gives 3/8 (or 0.375) cubic meters for the volume. A sphere with a diameter of 89.5 cm has that volume. In English units, take an ama as 20 inches or 5/3 ft., then the minimum mikva volume is 13.9 cubic ft. A sphere with a diameter of 3 ft. has that volume. I have no idea as to the source of the supposed minimum mikva volume of 25-35 cubic feet. Even a very large ama of 2 ft. only gives a volume of 24 cubic feet. [It simplifies matters a bit by using pi x D^3/6 as the volume of a sphere.]

    In any case, the gemara need not present a practical case. It merely wishes to make a point that the liquid substance of a fish is acceptable as a mikva medium.

  16. Reuven Meir calculated that we need an eye socket of 43 inches. The following is best I could do:

    "Shonisaurus sikanniensis is the largest marine reptile known, and the largest forms are for that matter the largest type of reptile known (exceeding the biggest terrestrial sauropods in size), the largest carnivorous animal, and among the largest animals ever to live. ... A specimen collected by the Tyrrell Museum in 2000 is 21 meters long, and, incredibly, even larger specimens are known; putting these animals in the size range of the larger baleen whales [Nicholls 2003]. But unlike baleen whales, which are filter feeders, Shonisaurus was a carnivore, ... The skull is massive, and the eye sockets alone are well over a meter across [Headden, 2004]. In life, had the largest eyes of any animal that ever lived.

  17. Actually, the last time daf yomi was in Menahot, I had to take one of my kids to the (Jewish with some knowledge of Judaism but not frum) pediatrician. He saw me learning gemara while waiting, and asked what I was learning. I kind of sheepishly fessed up to the gemara about which head a two headed person puts his shel rosh on, and he became very animated. Turns out he once had such a patient. I assume some sort of conjoined twins.

  18. Like these girls, the Hensel twins:

  19. Contrast:

    R' Slifkin: "Without doubting Chazal for a second, this cannot be explained or reconciled with modern science."


    Phil's post: "Shonisaurus sikanniensis'... eye sockets alone are well over a meter across."

    Could Chazal's use of the word "fish" include what would eventually be called ichthyosaurs?

    I look forward to R' Slifkin's comment on this.

  20. Well, the Torah seems to consider bats to be in the bird family. So, I don't see a problem with Chazal referring to any sea creature as a fish. (Oh, I'm not claiming that they spotted a live Shonisaurus. I'm not even claiming they found the bones of a dead one.)

  21. My objection was not to classifying a Shonisaurus as a fish.

  22. Then I'm really confused as to how I might be kidding you. I thought that when you wrote, "this cannot be explained or reconciled with modern science" you were implying that modern science has never found a fish-likecreature (alive or dead) with a meter-across eye socket.

  23. No, I meant that Chazal were mistaken in believing such a creature to exist. They were not talking about something that has been extinct for 100 million years!

  24. Oh, I didn't know that you were only allowing for a /currently existing/ creature, as opposed to /a/ creature. I guess the language of the gemara "if the eye were to dissolve" /does/ make it sound that the animal still exists, even though I was focusing on the word "if" -- meaning something like, "IF any animal with such a large eye CAN exist."

  25. In summary, I believe that your statement "Without doubting Chazal for a second, this cannot be explained or reconciled with modern science" can be understood in two ways:
    a) that such a creature currently exists (i.e. in the times of the Gemara)
    b) that such a creature did or can exist

    Perhaps you should explain to your correspondent that you meant (a) and not (b).

    I always wondered if Chazal had ever seen or heard of fossils. The Chinese at that time had. They sure didn't talk about them. There are references to "dragon" bones found in Wucheng, Sichuan, China over 2,000 years ago; these were probably dinosaur fossils. The Greeks and Romans may have seen them too, which could explain the ogre and griffin legends.

  26. If anyone actually looks at the Gemorah, it's clear that the discussion is about the liquid substances that can be in a mikva in place of (or in addition to) water.

    The braisa starts saying that one can tovel in anything that "originates in water" and continues to include in that category a dissolved fish eyeball. The sugya starts in the context of what can be added to existing mikva water to complete the needed 40 se'ah.

    In short, the Gemorah is discussing liquid substances, not the pools used for a mikva and not even the liquid that would make a complete 40 se'ah, just that could be added to water and still be kosher.

  27. It certainly wasn't understood that way... see Shulchan Aruch Yoreh Deah 201:33 and Darchei Teshuvah 201:159.


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