I found a fascinating introduction to Megillas Rus in one of my Mikraos Gedolos on the megillas which I want to share with everyone. (Click Here and Here and Here for Hebrew text.)
“Behold in the days that judges were judging, behold there was a famine in the land” (Rus 1:1). It is mentioned in the Medrish Rabba that 10 famines came to the world: 1. In the days of Adam Harishon… 2. In the time of Lemech… 3. In the days of Avraham… 4. In the time of Yitzchak… 5. In the days of Yaakov… 6. In the days of the judges judging… 7. In the time of Dovid… 8. In the days of Eliyahu… 9. In the days of Elisha… and 10. One will roll out and come to the world in the future… Rebbe Shmuel bar Nachmani said the most important famine was in the days of Dovid. It was supposed to come in the days of Shaul but because he would not have withstood the test it came in the days of Dovid. Rav Chisda bar Rav gave a parable to an attendant who had a box full of bottles and glasses and when he wanted to hang up the box he got a peg and fastened it into the wall to hang the box on it. For this reason all the famines did not come in the days where the people were unstable; rather at times when people were strong and able to stand up to the test at hand.
This medrish split the famines in half. Five were before the Torah was given and from Yaakov until the judges judged there was no famine in the world until the time came for the start of King Dovid’s service to spark and shine. For it is known the famous Chaza”l, ‘I found Dovid My servant. And where was he found? In Sedom.’ It is explicit from here that as long as the seed of Moav had not mixed with the House of Yehuda the light of Dovid was hidden and this reality was not revealed yet. However, in the days of this tzadik, Boaz, who took care of Rus the Moabite, who was the wife of Machlon, only then this reality (the line of Dovid Hamelech with the eventual advent of Moshiach) was revealed in the world.
Therefore, there was a place for the next famine to the rest which will return all the Jews. For this reason, this megilla started with the matter of the famine which was in those days and at the end discusses the lineage and birth of Dovid.
The Megilla is called Rus because all three are connected to each other: 1. The story of Rus eventually marrying Boaz, 2. revealing the roots of Dovid Hamelech’s lineage, and 3. the 6th famine that swept through the land. This connects to the 7th famine in the days of Dovid… where Dovid sought out Hashem in repentance, which then lead to the 8th famine in the days of Eliyahu Hanavi (who will herald in Moshiach). Then came the 9th famine in the days of Eliyahu’s student Elisha, and finally the last famine will be in the days of our righteous Moshiach; in his days the pasuk writes: ‘I will send a famine in the land, but not a famine for bread or a thirst for water but rather to listen to the word of Hashem.’
It’s also brought down in Medrish Rabba of Rus that Rebbe Ze’ira said that this megilla has no mention of purity or impurity, prohibitions or permissibility, so why was it written? To teach us how much good Hashem rewards those who act with kindness. For because Boaz saw the good heart of Rus, that she was imbued with a drive to do acts of kindness, which is one of the 3 signs of a Jew: 1. Merciful, 2. Bashful, 3. Doers of kindness, and Boaz saw in her all 3 attributes… Chaza”l say in a gemara in Shabbos 113b he saw modesty (which stems from the attribute of being bashful) by her, also her great humility when she said ‘I am not like one of your maidservants.’ All of these Boaz saw in Rus and recognized that she was the most fit from all the other women, and possibly she was the female Moabite which was prepared to bring into the world the light of the King Moshiach. For this reason he researched into her and thus the prophet Shmuel wrote at length this megilla to tell us who Rus was and how it came about that Rus was brought into the congregation of the Jews, who brought her on her journey. Therefore this megilla was called Rus to show that the main story was about her.
In the end it gives the account of the lineage from Peretz, the son of Yehuda, until the birth of Dovid and no more, because it also seems this megilla was written in order to trace the lineage of Dovid, in how Hashem orchestrated that Dovid would come out of Rus the Moabite. Hashem declared a famine on the land, and He put into the thoughts of Elimelech to move far away from Beis Lechem Yehuda to the land of Moav. His sons then married Moabite women, and Rus who came back with her mother-in-law, and wound up falling in “levirate marriage” to Boaz, to keep up the name of his family. They gave birth to Oved the father of Yishai, who was the father of Dovid. When Dovid came of age and killed Goliath, and King Shaul promised that anyone who would kill Goliath would marry his daughter, there was a huge argument amongst the sages of Israel if Dovid was permitted to enter the Congregation of Israel since it is written in the Torah that an Ammonite or Moabite may never enter the congregation of Hashem. But then Shmuel Hanavi sent word and poskined that only the males from Ammon and Moav were forbidden but the females were permitted (and Dovid came from a female Moabite), and they accepted this halacha. Since Shmuel saw that the main reason why Dovid was permitted to marry a Jewess was because of what he poskined, and if he would have been dead then they would have invalidated Dovid from marrying into the faith, therefore he wrote this megilla at great length to inform and show the world Dovid’s lineage.
In order that this megilla would not get lost through the years it was set into the holy scriptures of Tana”ch amongst the Kesuvim. Since Shavuos is the day we received the Torah, which is called the Torah of Kindness, and Dovid came from Rus the Moabite, one who was imbued with kindness, and he was born on Shavuos and died on Shavuos, and also the Torah and the name of Moshiach were created together before the creation of the world, and Dovid himself is the anointed one of the G-D of Yaakov, as it’s written ‘and Dovid My servant is a prince of theirs’ – therefore we read this megilla on the holiday of Shavuos.
From this introduction to the Book of Rus we see how Hashem has a master plan throughout the history of the world from before its creation to the very end and to see how it’s being orchestrated and played out with such exactitude and precision is an awesome sight to behold! We just must open our eyes, hearts and mind to see how Hashem’s master plan unfolds itself.