Hygiene in the Torah: Ancient Wisdom, Modern Insight

When we study the principles found in our classical sources, we are left in awe of the greatness of the sages, not only in Torah itself but also in matters far beyond the strictly religious sphere. One striking example is the extraordinary wisdom reflected in the laws of hygiene found in the Torah, the Talmud, and rabbinic literature.

In the modern world, awareness of hygiene and bodily cleanliness is widespread throughout Western society. Sterility and cleanliness are standard practice in every modern hospital. In ancient times however, there was almost no awareness of this crucial subject. Even at the beginning of the modern era, medical professionals had no real understanding of the tremendous importance of keeping medical tools clean.

When the first hospitals were established, doctors assumed that childbirth would become safer. To their astonishment, the death rate did not decline, but it increased dramatically compared to childbirth at home. Only in 1879 did Louis Pasteur prove that infection lay at the root of the problem. In many cases, women who died did so several days after giving birth. The mother would begin to shiver, her fever would rise, her pulse would quicken, her awareness would become clouded, her senses would fail, and then death would follow. All of this was caused by infections introduced during childbirth.

As early as 1817 Johann Peter Frank, often called the founder of public hygiene, published his work A Complete System of Medical Policing, in which he expressed admiration for the hygiene laws found in the Bible and the Talmud. But until the time of Pasteur, these principles were not truly implemented in practice.

The sterility measures introduced by Pasteur reduced maternal mortality to less than one percent of all births. To sharpen the contrast, it is worth noting that only a short time before this, the famous obstetrician William Hunter proudly used a pair of forceps covered in rust, claiming that the better the midwife, the thicker the layer of rust on the instrument.

When we examine the laws of the Torah, we see that the Creator embedded principles of cleanliness and sterility deeply within the Torah’s legal system.

Sterility and Medical Treatment in the Talmud

In rabbinic literature as well, we find remarkable awareness of cleanliness and sterility in daily life, and even more so regarding the conditions required for medical treatment.

Concerning the danger of metal touching an open wound, several examples are given. In the Talmud we are told that during a medical procedure one should use an instrument made of bone rather than metal, because “iron causes inflammation.” A similar instruction appears in another medical context, where the recommendation is to cut with barley rather than a metal instrument, again because metal causes harm.

Rashi explains that metal causes a wound, and another explanation is that it causes swelling.

In the laws of Shabbat there is a well known rule that Shabbat may be violated only in cases of danger to life or danger to a limb. Even so, the sage Shmuel ruled that a wound caused by metal, even if it is only external, carries danger to life and justifies violating Shabbat on its behalf.

Today, when we are aware of the danger posed by tetanus bacteria, which may be found on rusty metal and can be fatal even when entering through a small wound, it becomes easier to understand why Shabbat may be violated in such a case and why metal contact with an open wound requires such caution. It is astonishing to discover that the sages of the Talmud possessed awareness of this danger in an era when no one had any scientific understanding of such risks.

Preventing the Spread of Disease

From the many scattered teachings of the sages throughout the Talmud, one can see how highly they valued personal cleanliness.

Rabban Gamliel and his son Rabbi Shimon praised the people of the East because when they kissed one another, they did not kiss mouth to mouth, but instead kissed the back of the hand. In Tractate Derech Eretz, we are taught: “A person should not drink from a cup and then hand it to his fellow, because of danger to life.”

In the testament attributed to Rabbi Eliezer the Great, the reason is explained: perhaps the first person has some illness in his body, and some residue from his mouth may remain in the cup and make his friend ill as well.

Likewise, the sages taught that one should not bite from a piece of bread and then return it to the serving dish, nor should one bite from bread and then hand it to someone else.

From these examples it is clear that the sages understood that disease can be transmitted through saliva, many centuries before anyone in the scientific world imagined such a thing.

A similar teaching appears in Tractate Tamid, where several sages instructed their students that a cup should be rinsed before drinking from it, and also after drinking, lest another person later assume it is clean. If someone tasted a little water from a cup and then passed it to someone else to finish, some of the top water should be poured out first, so that any saliva residue from the first drinker would likely be removed.

The Jerusalem Talmud also warns against putting coins in one’s mouth, because they may carry contamination from sick people. Maimonides explains that the concern is dried saliva from people afflicted with skin diseases or other sources of bodily impurity and contamination, which could spread illness to others.

Dirty Hands and Hidden Danger

Bacterial contamination can also be transmitted through hands that are not sufficiently clean.

The Zohar states that “the poison of death rests on unclean hands,” meaning that something present on dirty hands can cause infection and death. Elsewhere, the Zohar teaches that a person’s table should be clean, that the body should be kept clean, and that a person should not approach food in an unclean state.

Out of concern for contagion, the sages declared: “If there is plague in the city, keep your feet inside.” They also warned against eating an egg that had passed through a street where a person suffering from a severe illness called ra’atan lived. A Midrash states that one should not walk on the downwind side of a leper within four cubits because of the danger from his breath. Likewise, a person afflicted with severe skin disease should not bathe together with another unless he informs him beforehand.

The sage Shmuel lived in Nehardea in Babylonia. When he heard of an epidemic in another region, he declared a fast to remove the danger, even though the illness was not in his own area. The reason given was that there were caravans traveling between the cities, and therefore the danger of contagion was real.

Sanitation and Public Health

The Torah strongly emphasizes the importance of both personal and public cleanliness, in an age when much of the world was immersed in idolatry, some forms of which included degrading and filthy rituals, and when the broader population had little concern for sanitation.

Remarkably, the Torah insists on sanitary rules even in wartime, when one would not normally expect concern for basic cleanliness. The Torah states:

“When you go out as a camp against your enemies, you shall guard yourself from every evil thing… You shall have a designated place outside the camp, and you shall go out there. You shall have a peg among your tools, and when you sit outside, you shall dig with it and cover your waste… and your camp shall be holy.”

The Torah therefore commands four clear sanitary measures: a designated place for relieving oneself, that this place must be outside the camp, that proper sanitary tools must be prepared, and that waste must be covered well to preserve environmental cleanliness. All of this is built directly into Torah law.

Cleanliness as a Religious Value

The sages took bodily cleanliness so seriously that they interpreted the verse in Lamentations, “You have cast off my soul from peace, I forgot what is good,” as referring to one who is denied access to a bathhouse, or at the very least to washing hands and feet in warm water.

It is told of Hillel the Elder that after teaching his students, he walked with them for a while. When they asked where he was going, he replied that he was going to perform a mitzvah. When they asked which mitzvah, he answered that he was going to the bathhouse, because caring for bodily cleanliness is itself a great mitzvah.

The Talmud also teaches that failure to wash the body can lead to boils and ulcers, failure to wash the head can damage eyesight, and failure to wash clothing can eventually disturb a person’s mental balance.

The sages further stated that sweat from the body is harmful and dangerous, and one should be careful not to let it enter the eyes, with the exception of facial sweat. Their commitment to cleanliness is also reflected in the Talmud’s list of ten things without which a Torah scholar should not reside in a city. One of those essential things is a bathhouse.

In Tractate Shabbat it is taught: “A person should wash his face, hands, and feet every day for the sake of his Creator.” Rashi explains that when one sees beautiful creatures, one blesses God for having such beauty in His world. There is therefore great value in preserving the divine image in a clean and dignified state.

Ventilation in the home was also considered important. The sages said: “Woe to the house whose windows open into darkness.” Good housing conditions mattered as well, and therefore they advised: “Spend less on food and drink, and more on your dwelling.” They also noted that living in crowded cities can be difficult, and Rashi explains that when houses are built too close together, there is not enough air.

Protecting the Health of the Body

Today, dentists can sometimes save lives. Many diseases remain hidden in the body long before they become visible, and dental professionals know that the condition of the mouth can reveal the condition of the body as a whole. There are illnesses whose earliest signs appear in the oral cavity.

Inflamed gums, bleeding after slight contact, loose teeth, and similar symptoms can alert a skilled dentist that the patient may be suffering from a broader systemic condition.

It is also well known today that neglecting dental hygiene can contribute to diseases affecting the abdomen, the heart, and other systems of the body. It is fascinating to find a description of such an illness in the Talmud. In Tractate Avodah Zarah there is mention of a disease called tzafdina, which spreads from the mouth into the digestive system. One of its signs is that when a person puts something into his mouth, the gums begin to bleed. Even today, a disease by this name is recognized.

Out of concern for physical health, the sages ruled: “A person should not drink water from rivers or lakes directly with his mouth or with one hand, unless it has first been filtered. If he does so, he endangers himself, because he may swallow a leech.”

The Tosafot explain that these are worms that can settle in the intestines and cause great suffering by drawing blood and harming the digestive system. Modern medical literature notes that leeches belong to a group of annelid worms and are often found in water. Many feed by sucking blood, and some can cause serious injury to humans. The Nile leech, for example, can attach deep in the throat and cause suffocation, or attach to the eyes and cause damage.

Rabbi Yochanan explained the verse, “By the rivers of Babylon, there we sat and wept,” by saying that the waters of the Euphrates killed more Israelites than Nevuchadnezzar did. In the Land of Israel, they had been accustomed to clean, healthy water, but the polluted waters of the Euphrates caused many deaths when their drinking habits suddenly changed.

The sages also taught that any sudden change in diet can lead to physical problems, saying: “A change in eating habits is the beginning of intestinal illness.” Thus, a person who is poor during the week and eats only sparingly may harm himself by overeating excessively on Shabbat.

Food Hygiene and Infection

We find further concern for food hygiene in Tractate Horayot, where the sages list several things that damage memory, among them eating food nibbled by a mouse or cat, and drinking leftover wash water.

As for food partially eaten by a mouse or cat, modern science has indeed identified parasites carried by such animals that can pass to human beings, even lodge in the brain, and cause serious damage.

Maimonides summarizes the rabbinic approach to preserving health in his Mishneh Torah. He writes that the sages forbade foods and drinks from which most people recoil, and they also forbade eating with hands that are dirty and contaminated, or from filthy vessels, because all of these things fall under the biblical warning not to make yourselves detestable.

Medical literature also notes that pigs are among the animals that can transmit infectious diseases to humans, partly because their digestive system closely resembles that of human beings. Astonishingly, a similar observation appears in the Talmud. When pigs began dying in the region of Rav Yehudah, he declared a fast because of the danger of contagion, explaining that pigs pass diseases to humans because their intestines are similar to those of people.

These are only a few examples from the vast body of Torah literature concerning hygiene, sanitation, and cleanliness. Together they paint a striking picture of the Torah’s profound concern for the health of the human body, no less than for the health of the human soul.