When I was a little kid, my older brother and I would take a magnifying glass into the hot South Texas Summer and try to start fires on leaves by focusing the suns light. If we had a lot of patience (and we were very young), we could sometimes get a leaf to smolder. In today’s Daf, we consider whether this would be a permissible cooking method on Shabbat.

All Sages agree that cooking in the sun is permissible. For instance, I could leave an egg on the hot pavement and, if it cooked, eat it on Shabbat. The Daf actually considers an egg left on a hot roof. I could also, presumably, brew sun tea. The Rabbis disagree about cooking with derivatives of the sun. The Daf speaks of scarves warmed in the sun. I am not sure how this works. I like to think of my magnifying glass. Could my brother and I use a magnifying glass on Shabbat to focus the sun’s rays and cook an egg (might take all day)? Some Rabbis feel that derivatives of the sun will be confused with derivatives of fire (back to putting our egg next to a hot kettle) and hold that we cannot use derivatives of the sun for cooking on Shabbat. Rabbi Yose disagreed, reasoning that if we can cook with the sun, we can cook with derivatives of the sun. According to a note in The Schoottenstein Edition, current law follows the Rabbis and does not allow cooking with derivatives of the sun.

We actually start the Daf with a discussion of returning cooked items to soaking in hot water, if we remove them on Shabbat. In general, we are allowed to do so and we are allowed to rinse items with hot water. However, salty fish are an exception because rinsing them with hot water causes them to cook a little.

We then turn back to our friends in Tiberias, who created an ingenious heat exchange method so they could have hot baths on Shabbat. They had a pipe with fresh water pass through a hot spring, which warmed the fresh water and emptied into a public bath. We have a lot of debate about why this practice is forbidden, which leads to a lot of discussion of bathing on Shabbat. In general, we can wash our hands and feet and face with water that was heated prior to Shabbat, but we cannot wash our entire body. A note in the Schottenstein Edition indicates that we should refrain from bathing at all, even in cold water on Shabbat.

We end with discussion of a general rule of interpretation. If we encounter two opinions in the Mishnah that disagree, and we find a third opinion mediates between them, we always accept the third mediating opinion. Of course the Daf ends with an exception to this rule.

If you are curious how all these rules around cooking work in a modern kitchen for Shabbat-observant Jews, I suggest you look at this article from My Jewish Learning: https://www.myjewishlearning.com/article/5-must-have-gadgets-for-shabbat-observant-jews/?utm_source=MJL_Maropost&utm_campaign=MJL_Daf_Yomi&utm_medium=email&mpweb=1161-18407-383775. You will see a lot of the principles around stoking a fire and cooking that we have been discussing for the last several days.