Midrash su Levitico 11:33

1) (Vayikra 11:33) ("And every earthen vessel where there shall fall of them into its midst") This tells me only of an earthen vessel. Whence do I derive for inclusion a natron vessel? From "and … earthen vessel." Whence would I (think to) include (earthen) tents (for tumah that I need a verse to exclude them)? I would reason thus: If (with) wooden vessels, where flat ones are tamei, tents are clean, then (with) earthen vessels, where flat ones are clean, how much more so should tents be clean! — No, if wooden tents are clean, it is because their atmosphere is clean. Should earthen tents, then, be clean, whose atmosphere is not clean? It must, therefore, be written ("earthen) vessel," to exclude (earthenware) tents (from tumah). Whence do I include (for tumah) earthen shards? From "and every earthen vessel."

1) I might think that vessels, too, acquire tumah in the atmosphere of an earthen vessel. It is, therefore, written (Vayikra 11:34): "all the food … and all drink": Food and drink acquire tumah in the atmosphere of an earthen vessel, but vessels do not. I might think that animal food, too, acquires tumah; it is, therefore, written "the food," the distinctive food of human beings. I might then think that I exclude (from tumah) animal food that one thought to use for human consumption; it is, therefore, (to negate this) written "all food (… shall be unclean"). I might think that even foul food (that is not fit for dogs, is included for tumah); it is, therefore, written "which shall be eaten," to exclude foul food. "food … shall be tamei": We are hereby taught that any amount of food becomes tamei. I might think that any amount (of food that is tamei) can confer tumah upon others; it is, therefore, written "which shall be eaten" (in one swallow). Only the size of an egg can confer tumah (upon others).

1) I might think that even a gourd which fell into the atmosphere of the oven and was not predisposed (to the acquisition of tumah) would become tamei; it is, therefore, written (Vayikra 11:34) "upon which water came." This tells me only of water (as a predisposing element). Whence do I derive the same for dew, wine, oil, blood, honey and milk? From "drink" — this is wine; "that is drunk" — this is blood, as it is written (Tehillim 110:7): "From a river, on the way, shall he drink (blood), wherefore he shall lift (his) head." Whence are other liquids derived (as predisposing elements)? From "and every drink." If "every drink," I would think (even) mulberry juice, fruit-juice, pomegranate juice, and (the juice of) all other kinds of fruits. It is, therefore, written "water." Just as "water" is characterized by the absence of a qualifying epithet, so I include dew, wine, oil, blood, honey, and milk, which have no qualifying epithets, and I exclude mulberry juice, pomegranate juice, and (the juice of) all other kinds of fruits, which have qualifying epithets.