The origins of Lag BaOmer as a minor festival are unclear. The earliest clear reference to the observance of Lag BaOmer is a brief statement by Isaac ben Dorbolo (12th century, northern France). It is found in his annotations to "Mahzor Vitry". He points out that Purim and Lag BaOmer always fall on the same day of the week, but he says nothing about the origin of the holiday. Lag BaOmer is also mentioned in the early 13th century by Avraham ben Nathan in his Sefer HaManhig. The Talmudist Menachem Meiri in his gloss to "Yevamot" 62b cites the Talmudic passage which states that during the time of Rabbi Akiva, 24,000 of his students died from a divinely-sent plague during the counting of the Omer. The Talmud goes on to say that this was because they did not show proper respect to one another. Meiri named Lag BaOmer as the day when, "according to a tradition of the geonim", the "plague" ended.