Lawrence H. Schiffman, Texts and Traditions, Ktav, Hoboken 1998, p.119-120.

In the time of the Mishnah the Rabbis debated the contents of the canon, that is, which books would be considered part of the Bible and which were not accorded this holy status. The Song of Songs, with its explicit sexual imagery, and Ecclesiastes, which could be understood to present a rather cynical view of the world, were the most hotly contested.

All Holy Scriptures defile the hands. 104 Song of Songs and Ecclesiastes defile the hands. Rabbi Judah says, “Song of Songs defiles the hands but there is a dispute regarding Ecclesiastes.” Rabbi Jose says, “Ecclesiastes does not defile the hands, and there is a dispute about Song of Songs.” Rabbi Simeon says, “[The status of] Ecclesiastes is one of the lenient rulings of the School of Shammai, and one of the strict rulings of the School of Hillel.” 105

Rabbi Simeon ben Azzai said, “I have a tradition from the seventy-two elders (of the Sanhedrin) that on the day when Rabbi Eleazar ben Azariah was appointed head of the Academy, it was decided that Song of Songs and Ecclesiastes defile the hands.” Rabbi Akiva said, “God forbid! No one in Israel disputed about Song of Songs, saying that it does not defile the hands. For all of eternity in its entirety is not as worthy as the day on which Song of Songs was given to Israel, for all the Writings are holy, but Song of Songs is the Holy of Holies. And if they disputed at all, they disputed only regarding Ecclesiastes.”

Rabbi Yohanan ben Joshua the son of Rabbi Akiba’s father-in-law said, “As according to Ben Azzai, so did they dispute and so did they determine [that both Song of Songs and Ecclesiastes are included in the canon].”

103. Trans. S. Berrin.

104. All books which are included in the biblical canon transmit defilement to those who touch them.

105. The School of Shammai takes the view that Ecclesiastes does not defile the hands, which is to say that it is not canonical. The School of Hillel rules that Ecclesiastes does defile the hands and is part of the canon.