R. Elijah ben Solomon Zalman of Vilna (Vilna Gaon, Gra, 1720-97) is a dominant figure in Jewish intellectual thought, his importance and prestige undiminished, as great today, if not greater, than in his own time. The Vilna Gaon’s extraordinary intelligence, expressed by his expertise in Torah at the age of three, outdistancing his tutors while a young child, his incredible proficiency over the entire expanse of the written and Oral Torah by nine, by which time he was already studying Kabbalah, accompanied by complete piety, are attested to by numerous reputable sources. More than seventy works, encompassing Bible, halakhah, Talmud, and Kabbalah, are attributed to the Vilna Gaon.

Tohorot (lit. "cleannesses") is the fifth tractate in the order of the same name according to the enumeration in the standard Mishnah. According to R. Hai Gaon it is the seventh. It is also the seventh in the Tosefta, if the three sections into which Kelim is divided there are counted as one. The name tohorot ("ritual cleannesses") is actually a euphemism for tumot ("ritual uncleannesses") since Tohorot deals essentially with the rules of the lesser degrees of uncleanness, effects of which last until sunset only. It details the laws of cleanness and uncleanness regarding foodstuffs and liquids, persons engaged in their preparation or consumption, and vessels employed in the process.