"What you would bake, bake": R. Yehoshua says: One who wanted "baked," would have it baked for him (of itself), and one who wanted "cooked" would have it cooked for him. R. Elazar Hamodai says: One who wanted something baked would taste all the "bakings" in the world (that he desired), and one who wanted "cooked" would taste all the "cookings" in the world. R. Elazar says: "on what is baked, bake; and on what is cooked, cook." How so? A festival that falls out on Friday, whence is it derived that it is forbidden to bake or to cook on it (for the Sabbath) unless he had made an eruv (tavshilin on Thursday for that purpose)? From "What you would bake, bake, etc." (i.e., bake on the strength of what you have already baked, and cook on the strength of what you have already cooked, so that the Friday baking or cooking is regarded as a continuation of that begun on Thursday and not as a preparation on the festival for the Sabbath).