Shavuot was one of the three pilgrimage festivals during the year. (The others: Passover and Sukot). The Rabbi’s later religiously transformed these agricultural festivals.
During Shavuot, the High Priest acted on behalf of the people. He presented a special Shavuot wave-offering, two loaves of bread made of wheat, the first products of the spring wheat harvest that begins just as the barley harvest comes to an end on the holy altar on Passover. Thus, Shavuot in Second Temple times celebrated the bounty of the spring harvest season.
The Festival is Transformed
In rabbinic times, a remarkable transformation of the festival took place. Based on the verse "In the third month after the children of Israel were gone forth out of the land of Egypt, the same day they came into the wilderness of Sinai," [Exodus 19:1] the festival of Shavuot became the anniversary of the giving of the Torah at Sinai.
Although Shavuot was known in the Bible by several names, including the Feast of the Harvest, the Festival of Weeks, and the Festival of the First Fruits, the sages added the name "Atzeret"-- withdrawal. In the Torah, the last days of the two other pilgrim festivals (Passover and Sukkot) are referred to as Atzeret to indicate on the seventh day of Passover and on the eighth day after the beginning of Sukkot, there must be a withdrawal from all menial labor.
Shavuot, too, was given the name of Atzeret by the Rabbis to emphasize the necessity of abstaining from menial labor on this holiday as well. They refused to adopt the theme of "Giving the Torah" because they thought it would be sacrilegious to limit the celebration of the giving of the Torah to a single day. To them, every day of the year should be considered as a day of receiving the Torah anew.
In traditional settings, the Book of Ruth is read on the second day of Shavuot.
Ruth, a widowed Moabite, married to a Jew follows her Israelite mother-in-law, Naomi, into the Jewish people with the famous words “whither you go, I will go, wherever you lodge, I will lodge, your people will be my people, and your God will be my God.”
She asserts the right of the poor to glean the leftovers of the barley harvest, breaks the normal rules of behavior to confront her kinsman Boaz, is redeemed by him for marriage, and becomes the ancestor of King David.
Read the full text of the Book of Ruth in Hebrew and English on Sefaria.org. (https://www.sefaria.org/search?q=book%20of%20ruth&var=1&sort=r)
The Talmudic tractate of Soferim (14:16), cites the Midrash of Ruth of with the giving of the Torah. Thus, such evidence establishes this practice by the time this Midrash was compiled.
(Tractate Soferim is one of the latest books of the Talmud, probably dating no earlier than the eighth century.)
There are many explanations given for the reading of Ruth on Shavuot. The most quoted reason is that Ruth’s coming to Israel took place around the time of Shavuot, and her acceptance into the Jewish faith was analogous of the acceptance of the Jewish people of God’s Torah.
A second explanation relates to genealogy. Since the Book of Ruth ends with the genealogy of David, whose forbearer Ruth was, it has been suggested that it is read on Shavuot because there is a legend that David died on Shavuot.
Another reason for the reading of Ruth on Shavuot is that its story takes place at harvest time, and Shavuot also occurs at the time of the spring harvest.
Customary Foods - Dairy
Every Jewish festival has special associated foods.
Although everyone agrees that the food of choice for is cheese, most typically blintzes, or a Sephardic equivalent such as bourekas, there are differences of opinion (some quite charming) as to why it is a custom.
Some derive the practice directly from scripture, saying we eat dairy to symbolize the “land flowing with milk and honey” ( ) promised to the Israelites, or that “milk and honey are under your tongue” ( ). These passages, along with “The precepts of the Lord are… sweeter than honey” ( ) also indicate we should eat honey, which is customary in some communities.
A sage discovered that the initials of the four Hebrew words in , which describe the sacrificial meal offering on Shavuot, spell mei halav (from milk), suggesting that dairy food is the acceptable dinner for the festival. At Sinai, the Israelites were considered to be as innocent as newborns, whose food is milk.
Those of kabbalistic [mystical] bent equate the numerical value of the word halav (milk) = 40 (‘het’=8, ‘lamed’=30, ‘vet’=2), with the number of days Moses spent on Mount Sinai receiving the Ten Commandments and other teachings ( ). Others look to the mountain itself, which is termed in Psalms mount of gavnunim (68:15), meaning many peaks. They connect that description with the Hebrew word gevinah, meaning cheese.
Scholars who trace all Jewish customs and rituals to practices common among various ethnic groups claim that spring harvest festivals characteristically featured dairy dishes, perhaps because cheese was produced during that season.
Along with blintzes and bourekas, cheesecake is a widely popular Shavuot item. Some eat kreplach, three-cornered dumplings that are often filled with meat but can be cheese filled or even vegetable filled. They are supposed to remind us of the Bible, which is comprised of three sections (Torah, Nevi’im and Ketuvim / Torah, Prophets and Writings), which was given to Israel through Moses, who was the third child of Amran (after Aaron and Miriam), following three days of preparation ( ) in the third month of the year ( ).
Excerpted with permission from Every Person’s Guide to Shavuot (Jason Aronson, Inc).
http://www.myjewishlearning.com/article/why-do-we-read-the-book-of-ruth-on-shavuot/?utm_source=MyJewishLearning+Newsletter&utm_campaign=3439b96317-EMAIL_CAMPAIGN_2017_03_24&; Rabbi Ronald H. Isaacs,