More on the measurements. First, the classic olive: k'zayit. Note that the measurements are presented as Halakhah le-Moshe mi-Sinai. They are not the subject of dispute. What does come to the fore is a question of how we know that these undisputed measurements are the measurements. Plus, determining the liquid measure of one's cheekful. Also, the essential question of whether (or when) the measurements are objective and when subjective. The disputes here are both about authority (mishnah vs. beraita) and the subjectivity question. Especially when you factor in people like the giant Og of Bashan, the classic example of someone whose subjective measures are different from the average. Also, defining eating be its effect (settling one's mind) vs. the logistics of amount and time span. Including Abaye's insistence that the only thing that matters is settling one's mind.