The Book "Kol HaTor," attributed to followers of Eliyahu of Vilna, deals at length with Mashiach ben Yosef (Messiah son of Joseph) and his role in bringing back the exiles and rebuilding the Land.

Kol HaTor – קול התור or "The Voice of the Turtledove" (a reference to Song of Songs 2:12) was written by Rabbi Hillel Rivlin of Shklov a disciple of the Vilna Gaon . The text deals with the Geulah (Era of Redemption) and describes its signs vis-a-vis an evaluation of a proposed 999 footsteps of the Moshiach’s arrival. The Vilna Gaon believed the number 999 to be intrinsically connected to the idea of Moshiach ben Yosef, he also felt that this number is alluded to in the gematria of his own name. It was first published in Hebrew by Rabbi Menachem Mendel Kasher in 1968 to whom the book was passed down over the generations.

We must know beforehand that the beginning of the Redemption will come gradually, a little at a time.  According to our Sages of blessed memory (Yerushalmi: Brachot, ch.  1), the redemption of Israel will come about little by little, like the first rays of light before dawn, [Micah 7:8] “though I sit in darkness, the Lord is a light to me, ” and [Prov.  4:18] “a light that increases more and more until the day is established.” Therefore, one should start any deed connected with the beginning of the Redemption, even to a small extent, as is written: [Jer.  3:14] “one from a city, and two from a family.”

The Gaon states that there is an important rule that anything that will occur when the Redemption is complete, will begin gradually at its beginning.  This is also true of rebuilding Jerusalem.  One should begin, even with one stone.  According to what is written, [Isa.  28:16] “behold I lay in Zion a foundation stone, a tried stone, ” for this stone will test the will to rebuild Jerusalem and to enlarge the site of its tent, and God will help us do this.  

We also asked the Gaon about what is revealed by the words, [Gen.  33:14] “I will direct it at my slow pace, ” that is, why must the beginning of the Redemption occur slowly? If it comes when it is a time of favor on the part of God in connection with gathering in the exiles of Israel, is the hand of God short [is it too difficult for God] to accomplish this task on a large scale all at once? The Gaon then explained to us that the period of the beginning of the Redemption will come into being if the Jews do not have the merit, which means when it does not come because of our righteousness.  In that case, if the Redemption comes suddenly, then on the one hand it will be impossible to bear the suffering that will come with the quality of Din, as explained above.  On the other hand, it will be impossible to accept the great light that will come all at once from the side of Lovingkindness.  We must understand all this beforehand in connection with the practical work involved in gathering in the exiles.

So who is Mashiach ben Yosef? Messiah ben Joseph (Hebrew: משיח בן יוסף), also alternatively known as Messiah ben Ephraim (Hebrew: משיח בן אפרים), is a Messianic figure peculiar to the rabbinical apocalyptic literature. One of the earliest known mentions of him is in (Sukkah52a, b), where three statements occur in regard to him, for the first of which Rabbi Dosa (c. 250) is given as authority. Rabbi Dosa reads Zechariah 12.10-12.12 as lamenting the death of Messiah ben Joseph.