Pesachim 18a, b

Another daf continues the discourse on ritual im/purity and liquids, foods, and vessels.

Here are a number of interesting points:

• If a cow drinks impure water, that water is nullified in its stomach and the cow does not transmit that impurity to other objects.

• Grammar is played with and used to provide proofs.  For example, one rabbi explains that yitma is 'it shall be impure' while yitameh is 'it shall render (another object) impure'.  Designating degrees of impurity rely how one interprets this word.

• Lo kach haya is 'this is not the correct interpretation'.

• Bo baYom is 'on this day', and it refers to the day when Rabban Elazar ben Azarya replaced Rabbi Gamliel as Nasi (see Berachot 27).  From that day forward, our Sages produced novel interpretations and halachot.

• The severity of an impurity might influence the degree of impurity rendered to another object.

• Hermeneutic principles used to unpack Torah halachot included a fortiori inferences (after the fact), verbal analogies, juxtapositioning, and analogies.

For some reason I found it particularly difficult to wad through today's daf.  It was not long, nor was it particularly complex. Perhaps it was me (I'm tired) but I think that we have spent quite some time on this notion of purity regarding liquid, food and vessels.  And this may be especially because I continue to feel as though my reading of this text is without the required foundation.