פירוש על בבא מציעא 41:16

Sesame [seeds] - are very small, so there is more exertion than [with] wheat; but their value is high.

One kav of sesame in four cubits, what is [the law], etc. One kav of dates, what is [the law], etc. - This is a wonder to me, why do I need all of these [questions]? Behold the main question of all of them is only whether the reason is because the exertion is great or because the [lost items] are not significant. And if you answered one of them, you have answered all of them. And does he need to go on like a peddler [to list all of the questions]? And one can say that not all of them were said in one study hall, but rather each and every one was inquired in its [own] study hall; and Rav Ashi (the editor of the Talmud) came and arranged them all like this. And there are many [cases] similar to this in the gemara. Or also (another answer), it is possible that there is a little bit of a reason that is in one that is not in the other. So even if you say that the reason is because they are not significant, whereas sesame is significant - nevertheless since there is excessive exertion, he would surely render it ownerless; or maybe the whole thing depends on significance, and since they are significant, he would not render them ownerless even if their exertion is excessive. And [with] a kav of dates or pomegranates - even though they are not significant, since there is only a little exertion, he would not render them ownerless; or perhaps the whole thing depends on significance, and since they are not significant, he would render them ownerless even if there is only a little exertion.