As noted on yesterday’s daf, our Gemara is in the midst of a lengthy discussion about magic and destructive forces – ideas that were popular during the Talmudic age that were not actively discouraged by the Sages if they were “harmless” in the sense that they did not involve idol worship or forbidden activities.
It appears that at least some of these popular beliefs were based on experience and diagnosis that were not fully understood centuries before microscopic germs had been seen through a lens. Thus, the Gemara informs us that the creature who is responsible for food is called “Nakid” (perhaps a play on the word naki – clean), while the creature responsible for poverty is called “Naval,” and that a house where crumbs are left on the floor is visited by Naval, while a house where proper care is taken with food is visited by Nakid. As the Aruk points out, the Gemara is not only “introducing” us to metaphysical forces that lurk in the house, but is also teaching basic rules of cleanliness. Homes where basic rules of sanitation are kept will be “ruled” by the Lord of Food, while places where hygiene is lacking and food is not treated in a clean, respectful manner will be governed by the Lord of Poverty.
Other recommendations made by the Gemara on our daf include Rav Yosef’s admonition about activities that lead to a loss of vision (note that Rav Yosef, himself, was blind). The first such activity is combing hair when it is dry. This may refer to a brief period of vision loss when vigorous combing – particularly of dry hair that is stuck together – may affect the scalp and create a nerve reflex that may cause partial loss of sight for a short time. The second activity that he mentions is drinking in a manner that he call “tif tif.” This may refer to someone who drinks the dregs of a wine barrel, where the alcohol level is higher than normal. The high alcohol level may cause a slight poisoning that can lead to partial blindness. Rav Yosef’s final recommendation is to avoid putting on shoes when your feet are still wet. This, too, may be explained by suggesting that rheumatic damage can affect the optic nerve, causing visual disorders.