Rabbi Yoḥanan says: It is preferable to drink from a cup of witches than a cup of lukewarm water; that is so only if it is in a metal vessel, but in an earthenware vessel it does no harm. And even in a metal vessel we say lukewarm water is unhealthy only where one did not cast flavorings into it, but if flavorings were thrown into it, it does no harm. And even if flavorings were thrown into it we say it is harmful only if the water had not been boiled, but if it had been boiled it can do no harm.
We are aware of danger in lukewarm water inasmuch as the low-level heat encourages the development of bacteria. Two opposite processes would protect from this development:
- freezing, which limits oxidation and decay
- boiling, which destroys microscopic organisms.
Leaving different types of drinks in metal containers also poses a variety of risks that are connected with chemical reactions (e.g. rust) between the metal and substances in the drink.
Rabbi Yoḥanan also said: If a person is left a fortune by his parents and wishes to dissipate it, he should wear linen garments, use glass vessels, and hire laborers and not sit with them. ‘He should wear linen garments’ – especially of Roman linen;‘use glass vessels’ – especially white glass;‘and hire laborers and not sit with them’ – especially laborers that work with oxen, which can cause much damage.
In all likelihood, what is referred to as “white glass” is actually transparent glass, which is much more difficult to make than ordinary colored glass. To make transparent glass, the purest raw materials need to be prepared. During Talmudic times, such glass was rare and expensive. Usually utensils made from such glass were also more delicate, and thus, more breakable.