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Visual Aids in Halacha


This week’s article explores the use of visual aids within the framework of halacha. How do these tools impact halachic rulings? What prompted the Chasam Sofer to cease using vinegar? Is there a prohibition against consuming microscopic organisms? Is it permissible to eat a fish if its scales can only be detected with a magnifying glass?  Is it possible to validate or disqualify a Torah scroll based on evidence from a magnifying glass? How should the square shape of tefillin be measured? What size of insects render food forbidden? Our article this week delves into these questions and more.

Eating Worms Invisible to the Naked Eye

In this week’s Torah portion, it is stated (Bamidbar 6:3): “He shall abstain from new wine and aged wine; he shall not drink [even] vinegar made from new wine or aged wine, nor shall he drink anything in which grapes have been steeped, and he shall eat neither fresh grapes nor dried ones.” The Torah forbids a Nazir from consuming wine as well as wine vinegar. This pasuk is the source for a central halachic principle that significantly impacts our lives, as we will see further on.

The Vinegar Controversy

In Vilna, over 200 years ago, there lived a prominent scholar and Kabbalist, Rabbi Pinchas Eliyahu HaKohen. He was also well-versed in the sciences, and authored a unique sefer called Sefer Habris. This fascinating book covers a wide array of fields, combining his extensive knowledge of Torah, Kabbalah, and science. Based on the scientific discoveries at the time, Rabbi Pinchas Eliyahu raised many halachic questions that had not yet been discussed, such as the question of the international date line. Many leading Torah authorities of his generation (Rabbi Akiva Eiger, Shulchan Aruch OC 568:1; Chochmas Adam 68:1; Tiferes Yisrael Taharos 3; Drashos Chasam Sofer 3:83; Pischei Teshuvah YD 116:3; Rav Pe’alim 2; Sod Yesharim 3, among others) quote him, and in some instances — accept his opinions as the halacha.

One of the halachic issues raised in his book (Essay 6:3) was the issue of microscopic organisms. The scientific community had just discovered the microscopic world of living organisms, which raised the question of consuming those living creatures. One such example is the organisms that live in vinegar. When they examined vinegar with microscopes, scientists found it was teeming with countless living creatures—microscopic organisms—which Rabbi Pinchas Eliyahu refers to as tiny worms. In light of this startling discovery, he firmly stated that drinking vinegar is prohibited.

Consuming Invisible Worms

Rabbi Pinchas Eliyahu argued that vinegar production involves microscopic organisms that consume sugar or alcohol and produce vinegar. Our current understanding confirms that — bacteria known as Acetobacter carry out a chemical process that transforms the alcohol into acetic acid, giving vinegar its sour taste. In fact, all alcohol production involves similar microorganisms that consume sugar and secrete alcohol. Once the alcohol concentration reaches a certain level, it kills these organisms, halting fermentation. According to Rabbi Pinchas Eliyahu’s view, it would also be forbidden to drink wine during fermentation, as it still contains living microscopic organisms.

The Maharam Schick (YD 105), a prominent student of the Chasam Sofer, concurs with Sefer Habris’ assertion, ruling that if vinegar is shown to be full of tiny worms, it must be filtered accordingly. However, he posits that if the worms have not separated from the vinegar, they are permissible, just like a detached fruit that becomes worm-infested, where the worms are considered part of the fruit itself. This ruling resulted in special guidelines that the poskim provided for using vinegar without boiling.

The Maharam Schick testifies that his teacher, the Chasam Sofer, would avoid consuming vinegar.

In later generations, even those who generally follow the Chasam Sofer’s rulings did not adopt this stringency. It appears that the Chasam Sofer, upon hearing of a potential issue, took on the above-mentioned precautions just until he could clarify the facts. Based on further studies in the matter, even those who adhere to the Chasam Sofer’s approach do not avoid using vinegar.


This issue sparked significant halachic debate. With scientific advancements, other halachic authorities argued (Aruch HaShulchan YD 84:36; Rabbi Chaim Soloveitchik of Brisk, cited in Igros Moshe YD 2:146) that microorganisms cannot be seen as halachically prohibited living creatures which are forbidden to ingest, since that would also forbid breathing, as the air is full of bacteria! This matter necessitated defining the status of microscopic organisms.

Why is Vinegar Permissible

The Chochmas Adam (Binas Adam, Shaar Isur V’Heter 34:49) challenges Rabbi Pinchas Eliyahu’s claim, arguing that it is explicitly stated in this week’s Torah portion that only a Nazir is prohibited to drink wine vinegar, indicating that one who is not a Nazir is permitted to do so, even though it contains microscopic organisms.

He offers further evidence from the Megillahs Rus which is read on Shavuos. In 2:14, Boaz invites Rus to eat in the field, saying: “Come here and partake of the bread, and dip your morsel in the vinegar.” This pasuk clearly indicates that dipping bread in vinegar and consuming it is permissible, despite the presence of microscopic organisms in vinegar.

As for the suggestion made by Sefer HaBris that boiling and filtering vinegar through a fine cloth could remove these tiny creatures, the Chochmas Adam dismisses this idea, arguing that the Torah would not permit vinegar without specifying it was boiled. He contends that there is no oral tradition indicating that only boiled vinegar is permitted.

As for worms in vinegar that can be detected when the vinegar is examined in sunlight, he rules they should be treated similarly to those found in detached fruit: they are permitted as long as they remain inside the fruit. Once they leave and return, or if found outside the fruit, they are forbidden.

Halachic Perspective on Microscopic Organisms

The Chochmas Adam’s ruling forms the foundation for rulings by prominent poskim, including Rabbi Chaim Soloveitchik of Brisk and Rabbi Shlomo Zalman Riger of Brisk (as cited in Igros Moshe, YD 2:146; Aruch Hashulchan YD 84:36). They concluded that the Torah prohibits only that which is visible to the naked human eye. Anything visible only through a magnifying glass or microscope is not forbidden. However, if something can be seen with the naked eye under direct sunlight or good lighting, it is prohibited. The principle is that the Torah was given to humans, not angels, and pertains to what can be seen with the unaided human eye. Modern scientific discoveries about microscopic organisms do not change this halacha.

The Aruch Hashulchan (84:36) further argues, that although water contains microscopic living organisms, we all drink water; and although the air is filled with microscopic organisms, the Torah permits breathing. He adds that if tiny creatures are visible to the naked eye under sunlight or good lighting, they are strictly prohibited.

Microscopic Fish Scales

The Tiferes Yisrael (Avodah Zarah 2:3) recounts an episode involving a scholar from a previous generation who wished to permit a fish with scales visible only through a magnifying glass. The Tiferes Yisrael explains that such a fish is prohibited, as only scales visible to the naked eye render a fish kosher.

Checking Bedikah Cloths

Rabbi Shlomo Zalman Riger, the dayan of Brisk (cited in Igros Moshe YD 2:146), ruled blood only visible by magnifying glass or microscope cannot render a woman impure. Rabbi Eliyahu Falk (Machzeh Eliyahu, 91) supports this principle, stating that throughout the Torah, things not visible to the naked eye should not be considered.

In one notable incident, the rabbi of a community left, and his successor lacked expertise in identifying blood stains. Some community members, many of whom were senior doctors, suggested laboratory tests to detect blood on cloths. These tests revealed that almost every cloth had minute traces of blood, yet the Torah does not prohibit such findings.

Measuring Tefillin

Rabbi Shlomo Zalman Riger also ruled (cited in Igros Moshe, YD 2:146) that using a surface gauge to verify the precise squareness of tefillin is unnecessary. As long as the tefillin appear square to the naked eye, they are considered mehudar. Rabbi Moshe Feinstein (ibid.) disagrees, stating that even a slight visible discrepancy is acceptable. Some contemporary poskim suggest striving for tefillin to be square within a 1mm tolerance, but consider further precision unnecessary. The Ma’adanei Yom Tov (Tefillin, 9:40) notes that absolute precision is impossible for tefillin, and the Torah demands only humanly achievable accuracy.

Magnifying Glasses for Sefer Torah, Tefillin, and Mezuzah Scrolls

In Dovev Meisharim, Rabbi Dov Berish Weinberg of Tschebin stipulates that determining the kashrus of Sefer Torah, tefillin, or mezuzos with a magnifying glass is impossible. Whether it’s detecting prohibited connections between letters, or gaps where connections should be, the naked human eye is the sole arbitrator. This applies both to koshering and disqualifying scrolls.

Checking Food

Concerning food, She’eilas Ya’avetz addresses the prohibition of consuming rice infested with “milben,” (rice weevil). This is a tiny mite measuring 0.2 mm. Thorough inspection is necessary to eliminate the weevil, and he lists several methods for doing so, one of them through the assistance of a magnifying glass.

Of the Chasam Sofer we are told (Mihangei HaChasam Sofer 10:18) that he would hire bochurim specifically to check the lettuce for the seder with a magnifying glass.

On the other hand, Rav Shlomo Kluger (Tuv Ta’am Vada’as last kuntress, chapter 53) insists that tools to amplify vision cannot be used to make halachic determinations. Where Chazal prohibit something without checking, the original prohibition remains until determined clean by the human eye, because only the naked human eye can do the checking. Even where we are unable to check, and the amplifying apparatus reveals the truth, the prohibition remains in place.

As proof to this ruling, he refers to the Gemara (Pesachim 37a) where Chazal prohibit matzos with artistic decorations out of concern that taking the time to decorate a matzah presents a risk of the matzah becoming chometz. Baytus ben Zonin asked the sages if he could use a stamp to decorate the matzah, a method that takes only a second to imprint in the dough. The sages responded that since decorated matzah is prohibited on Pesach, this prohibition applies universally, even when there is no actual risk of the dough becoming chometz.

Contemporary halachic rulings largely align with the She’eilas Ya’avetz, permitting the use of a magnifying glass to determine kashrus status. For instance, if there is a questionable stain that might be blood, but under magnification appears as a concentrated yellow, the magnifying glass can be relied upon to make a determination. Esrogim are another area in which magnifying glasses can be of aid: clarifying whether a flaw existed before or after picking, or if something is a spot or a missing part of the esrog. This is why many rabbis employ a magnifying glass when making halachic rulings.

However, Rabbi Shmuel Wosner (Shevet Halevi 7:122) maintains that while halacha follows Rabbi Shlomo Kluger, and magnification doesn’t nullify prohibitions, where rice has been checked by a magnifying glass and is no longer infested, it does not require checking anymore, and therefore can be consumed without concern.

Contemporary Halacha

In halacha we distinguish between insects and other organisms.

While insects are visible to the naked eye, they are often difficult to detect for several reasons:

  1. Camouflage: Insects have camouflage colors that resemble their habitat.
  2. Appearance: Insects can appear as black dots, indistinguishable from dirt without a magnifying glass.
  3. Vision Quality: Detecting these insects requires good vision.

Organisms, on the other hand, are not prohibited, even large ones, such as amoebas, despite being visible to the naked eye. Contemporary poskim have determined that, the opinions of Sefer Habris notwithstanding, these organisms are not prohibited because their life processes differs significantly from those of insects. Therefore, they do not fall under the prohibition of sheretz (creeping creatures), even if they are visible to the naked eye.

Insects Appearing as Black Dots

Rabbi Shmuel Wosner (Shevet HaLevi 7:122) discusses worms that appear as black dots and can only be identified as such with a magnifying glass. He questions whether these should be considered worms and prohibited. If the black dot moves, for example, when touched with a fingernail, it is sufficient to be prohibited as an insect, even if its form is not discernable.

Sharp Eyesight

This raises the question of whose eyesight should be considered the standard. A person with poor vision cannot claim they do not see worms on lettuce and therefore eat it without thorough inspection or cleaning. The Shelah (Shaar HaOsiyos, Kedusha) writes that the inspector must have good and precise vision. The Chasam Sofer (OC 132) declared in his Shabbos HaGadol speech that those with poor vision should avoid eating lettuce altogether and opt for horseradish for the mitzva of marror to avoid transgressing Torah prohibitions.

Rabbi Moshe Vaya (Bedikas HaMazon KeHalacha 2:6, p. 101) rules, based on the D’var Shaul and Yosef Da’as (cited in Darchei Teshuva 84:15), and Rabbi Shlomo Zalman Auerbach (Halichos Sadeh 51), only worms that cannot be seen by someone with the sharp eyesight are permitted. Conversely, Shevet HaLevi (Volume 7, Chapter 122; Paragraph 125:2) and Machazeh Eliyahu (91) clarify that halacha is determined by one with average vision, and the presence of people with sharper eyesight does not prohibit such worms.

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