The third perek of Massekhet begins on today’s daf and the Gemara turns its attention to the laws of cooking. Cooking on is explicitly prohibited in the Torah, and this prohibited labor is listed among the thirty-nine primary categories of labor prohibited on. Since cooking is generally completed as begins, the discussion of the labor of cooking precedes the discussion of the other prohibited labors in the sequence of this tractate.
This chapter occupies itself primarily with the clarification and precise definition of the prohibited labor of cooking. That undertaking carries with it numerous problems.
Unlike other categories of labor, there is an interval between the action and the desired result. It is a process, and therefore the question arises: At what stage in the process can it be said that an act of cooking has been performed? Shall we say that one who undertakes any action in the course of the entire process is considered to have engaged in that prohibited labor? Or perhaps, that is the case only with regard to one who initiates the process? Moreover, since the cooking process, once initiated, continues without the need for any additional action by the one cooking, the question can be raised: Is the mere act of placing an item on the fire defined as labor, or is it considered an incomplete segment of that labor?
There is a question as to whether the essence of the labor of cooking is transforming inedible into edible, unusable into usable, or whether it is the act of cooking that is prohibited, independent of the result. In practical terms, is it prohibited to further cook a cooked item?
The fundamental definition of cooking requires clarification and precision. In a very general sense, one could posit that cooking or baking are activities that render substances fit for use by means of heat. However, that leaves open the question of whether any activity that renders a substance usable is considered cooking, or perhaps, the essence of cooking is merely the softening or hardening of that substance? It is also important to clarify whether the prohibited labor of cooking applies to all substances, or perhaps only to food, or perhaps only to specific types of food.
Additionally, it must be ascertained whether the definition of cooking is restricted to the use of fire or whether it extends to other sources of heat. Similarly, is there a distinction between natural sources of heat and artificial ones in this context?
Most of these problems are resolved in various manners in this chapter. Some are discussed in Chapter Four and some in Chapter Seven, which discusses the primary categories of prohibited labor.