פירוש על תרומות 5:8

עד שנפלה אחרת – another Seah of heave-offering/Terumah.

If a seah of terumah fell into a hundred [of hullin], and before he could take it out, another fell in, the whole becomes forbidden. Rabbi Shimon permits it. Once the second seah falls into the mixture, it is now 2/102 terumah, and that is more terumah than the required 1/101 (one seah of terumah falling into one hundred seahs of hullin). Therefore, the sages say that the whole pile is medumma and is forbidden to non-priests. What they are in essence saying is that until the seah is removed, the pile is treated like terumah. Rabbi Shimon holds that as soon as the terumah falls into the 100 hullin, the terumah is neutralized and it is treated as if it no longer exists. Therefore, if another seah of terumah falls in, it is treated as if it fell into a pile of 100 seahs of hullin and it too is neutralized.

הרי זו אסורה – that it is like they fell at one time.

ור' שמעון מתיר – and it was known known to about first falling until it fell a second time, Rabbi Shimon admits that it is like the case when they fell at the same time. But he disputes where it was known to him in the meantime and he did not have the opportunity to lift it up until another fell, Rabbi Shimon holds that since he was about to lift it up is like something that has been lifted up, and he goes according to his reasoning , that he holds in general (Tractate Pesahim 13b; Tractate Bava Kamma 76b): He who is about to be sprinkled is considered as if it was sprinkled, but the Sages state that now, hoever, it was not lifted, and the Halakha is according to the Sages.