I’m putting this up because I thought it too interesting to fall between the cracks. Also, Rav Simcha Soloveitchik says it’s brilliant, so even discounting for גוזמה and חנופה, it must be ok. Please forgive the peculiarities – I don’t have time to make it pretty.
Reb Zeira’s famous rule (for example in Menochos 13b) is that כל הראוי לבילה אין בילה מעכבת בו וכל שאינו ראוי לבילה בילה מעכבת בו. Something the Torah says is part of a Mitzva is sometimes essential and sometimes not. Where the Torah does not make it fundamentally essential, the rule tells us that although you can do without, that is only where under the circumstances you could have done the act. IF, however, the circumstances are such as to make it impossible to do the act, then you can not fulfill the Mitzvah.
The first application is by a Korban Mincha: Most Menachos are meant to be mixed with oil. Failure to mix the oil into the flour would not render the Mincha unfit: you simply will have missed the opportunity to do the mitzva of “mixing the flour with oil.” But this is true only where you could have mixed it. Where you could not mix it, then failure to mix renders the Mincha unfit.
Nedorim 73a, that even though a man can be meifir without hearing the neder, a cheresh cannot be meifir.
Yevomos 104b, that even though reading is not me’akeiv, a mute man or woman cannot do chalitza.
BB 81b, you need ro’ui to read by Bikurim.
Taz in OC 689 that a deaf person is not chayav Birkas Hamozon, Megilla, Krias Shema based on kol horo’ui. See also Shagas Aryeh 6 – 7.
Kiddushin 25 on Ro’ui le’biyas mayim regarding beis hastorim.
In fact, the Sdei Chemed in Klal Choph 37 brings the Mas’as Binyomin who says the rule doesn’t apply by derbabonons, proving that from the fact that if you’re during shmoneh esrei shomei’a k’oneh works, even though you’re not allowed to talk. Many argue, and he brings many that say that indeed there is no s’k when you’re not allowed to talk.
