Shemini, Section 7
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."