Introduction Rabbi Dostai’s teaching is a continuation of the previous mishnah. Whereas there the topic was one who interrupts his learning, here the topic is one who forgets that which he has already learned.

Rabbi Dostai ben Rabbi Yannai said in the name of Rabbi Meir: whoever forgets one word of his study, scripture accounts it to him as if he were mortally guilty, as it is said, “But take utmost care and watch yourselves scrupulously, so that you do not forget the things that you saw with your own eyes” (Deuteronomy 4:9). One could [have inferred that this is the case] even when his study proved [too] hard for him, therefore scripture says, “that they do not fade from your mind as long as you live” (ibid.). Thus, he is not mortally guilty unless he deliberately removes them from his heart. The problem of forgetting that which one has already learned is one of the most serious problems that the rabbis encountered. Although we have the Mishnah in front of us in a book, for the rabbis who lived during this period the Mishnah and the Talmud and all of their works were oral. Therefore one had to repeat his learning frequently in order to commit it to memory. Indeed the meaning of the word “mishnah” is to teach through repetition. One who forgets his learning is in some ways worse than one who has never learned, because the one who forgets had knowledge at one point but was careless in its preservation. The second half of Rabbi Dostai’s statement is an essential reservation on the first half. One who has trouble learning, but genuinely tries his best, is not to be faulted for his forgetfulness. Rabbi Dostai recognizes that remembering the complicated oral Torah is not easy, and that not all people are built for such types of intellectual activity. Therefore he clarifies that only one who forgets out of negligence or on purpose neglects his study is mortally guilty. Perhaps I should emphasize here to those who have been learning Mishnah Yomit for some time that review of the material is as important, if not more important, than continuing to learn new material. By reviewing that which you have already learned your background in Jewish learning will increase. By analogy, think how much better you remember a movie after you have seen it two or three times. Reading through mishnayoth which you learned in the past is essential.