Introduction to Old Testament "Feast Days"

I think it is tragic how unaware we are of the basic details of the Old Testament holidays. I think it would greatly improve our education as Catholics to learn a bit about them, especially so we can see that living liturgically has deep roots in the Old Testament, and how these OT holidays were foreshadowing of Jesus. For this post, I have decided to do some research and share what I've found, since I have never really looked into this myself and was never taught much on this subject. I might have a few details that need correction, so I welcome your feedback! 

The most important chapters on the Jewish holidays is found in Leviticus 23 and Numbers 28. First we'll look at what Moses says in Leviticus 23 as God Himself lays out the Seven Major Feasts:

1 The Lord spoke to Moses, saying, 2 “Speak to the people of Israel and say to them, These are the appointed feasts of the Lord that you shall proclaim as holy convocations; they are my appointed feasts.

[Saturday] 3 “Six days shall work be done, but on the seventh day is a Sabbath of solemn rest, a holy convocation. You shall do no work. It is a Sabbath to the Lord in all your dwelling places.

4 “These are the appointed feasts of the Lord, the holy convocations, which you shall proclaim at the time appointed for them.

[Passover & Unleavened Bread] 5 In the first month, on the fourteenth day of the month at twilight, is the Lord's Passover. 6 And on the fifteenth day of the same month is the Feast of Unleavened Bread to the Lord; for seven days you shall eat unleavened bread. 7 On the first day you shall have a holy convocation; you shall not do any ordinary work. 8 But you shall present a food offering to the Lord for seven days.”

[Feast of First-fruits] 9And the Lord spoke to Moses, saying, 10 “Speak to the people of Israel and say to them, When you come into the land that I give you and reap its harvest, you shall bring the sheaf of the first-fruits of your harvest to the priest, 11 and he shall wave the sheaf before the Lord, so that you may be accepted. On the day after the Sabbath the priest shall wave it. 12 And on the day when you wave the sheaf, you shall offer a male lamb a year old without blemish as a burnt offering to the Lord. 13 And the grain offering ...14 And you shall eat neither bread nor grain parched or fresh until this same day, until you have brought the offering of your God: it is a statute forever throughout your generations in all your dwellings.

[Feast of Weeks / Pentecost] 15 “You shall count seven full weeks from the day after the Sabbath, from the day that you brought the sheaf of the wave offering. 16 You shall count fifty days to the day after the seventh Sabbath. Then you shall present a grain offering of new grain to the Lord. 17 You shall bring from your dwelling places two loaves of bread ...18 And you shall present with the bread seven lambs ...21 And you shall make a proclamation on the same day. You shall hold a holy convocation. You shall not do any ordinary work. It is a statute forever in all your dwelling places throughout your generations.

22 “And when you reap the harvest of your land, you shall not reap your field right up to its edge, nor shall you gather the gleanings after your harvest. You shall leave them for the poor and for the sojourner: I am the Lord your God.”

[Feast of Trumpets] 23 And the Lord spoke to Moses, saying, 24 “Speak to the people of Israel, saying, In the seventh month, on the first day of the month, you shall observe a day of solemn rest, a memorial proclaimed with blast of trumpets, a holy convocation. 25 You shall not do any ordinary work, and you shall present a food offering to the Lord.”

[Day of Atonement] 26 And the Lord spoke to Moses, saying, 27 “Now on the tenth day of this seventh month is the Day of Atonement. It shall be for you a time of holy convocation, and you shall afflict yourselves and present a food offering to the Lord. 28 And you shall not do any work on that very day, for it is a Day of Atonement, to make atonement for you before the Lord your God. 29 For whoever is not afflicted on that very day shall be cut off from his people. 30 And whoever does any work on that very day, that person I will destroy from among his people. 31 You shall not do any work. It is a statute forever throughout your generations in all your dwelling places. 32 It shall be to you a Sabbath of solemn rest, and you shall afflict yourselves. On the ninth day of the month beginning at evening, from evening to evening shall you keep your Sabbath.”

[Feast of Booths/Tabernacles/Tents] 33 And the Lord spoke to Moses, saying, 34 “Speak to the people of Israel, saying, On the fifteenth day of this seventh month and for seven days is the Feast of Booths to the Lord. 35 On the first day shall be a holy convocation; you shall not do any ordinary work. 36 For seven days you shall present food offerings to the Lord. On the eighth day you shall hold a holy convocation and present a food offering to the Lord. It is a solemn assembly; you shall not do any ordinary work.

37 “These are the appointed feasts of the Lord, which you shall proclaim as times of holy convocation, for presenting to the Lord food offerings, burnt offerings and grain offerings, sacrifices and drink offerings, each on its proper day, 38 besides the Lord's Sabbaths and besides your gifts and besides all your vow offerings and besides all your freewill offerings, which you give to the Lord.

[cont Feast of Booths/Tabernacles/Tents] 39 “On the fifteenth day of the seventh month, when you have gathered in the produce of the land, you shall celebrate the feast of the Lord seven days. On the first day shall be a solemn rest, and on the eighth day shall be a solemn rest. 40 And you shall take on the first day the fruit of splendid trees, branches of palm trees and boughs of leafy trees and willows of the brook, and you shall rejoice before the Lord your God seven days. 41 You shall celebrate it as a feast to the Lord for seven days in the year. It is a statute forever throughout your generations; you shall celebrate it in the seventh month. 42 You shall dwell in booths for seven days. All native Israelites shall dwell in booths, 43 that your generations may know that I made the people of Israel dwell in booths when I brought them out of the land of Egypt: I am the Lord your God.”

44 Thus Moses declared to the people of Israel the appointed feasts of the Lord.

This is kind of a long chapter, but it is important and fascinating to learn the main Israelite "holidays" that involve the common concepts of resting, sacrificing, and a solemn gathering of the community ("holy convocation"). Now let's breifly break down the seven major original holidays per this chapter and how they relate to the New Testament: 

• Passover (one day, 1/14) - This is probably the most well known holiday, with the Passover Lamb in Exodus being sacrificed to free the Israelites from bondage. Jesus is called our Passover (1 Cor 5:7), as He was crucified on Passover and frees us from bondage to sin.
  
  
• Unleavened Bread (seven days long, 1/15-1/21) - This feast immediately follows (and is closely tied to) Passover day. It reminds the Israelites that when they fled Egypt, they didn't even have a few hours spare time to let the leaven/yeast in the bread rise, so they had to simply mix the bread dough barely let it bake into flatbread and rush out, similar to how we rush out of the house in the morning without any time to prepare a real meal and grab whatever is convenient. The Bible often speaks of the dangers of leaven/yeast in the spiritual sense. In normal bread, the ingredient of yeast (leaven) is only 1% of the total ingredients for bread, yet despite being such a small percent of the bread, it plays a major role in making the bread rise into a full fluffy loaf. Otherwise, the bread is flat and cannot be enjoyed or made into a sandwich. This means in the spiritual sense, "yeast" is any small idea or teaching that greatly affects how one believes and behaves. Jesus said "beware of the leaven of the pharisees and the leaven of Herod" (Mark 8:15). Not only do religious leaders have a tendency to introduce bad 'tiny ideas' into us that sound good, to make us believe the wrong things, such as sexual impurity not harming anyone (when in fact impurity is very damaging), but also secular leaders introduce bad 'tiny ideas' that sound good, such as 'separation of church and state', which ultimately undermine the faith (since secular law is not based on any objective truths). Paul also speaks of the spiritual unleavened bread in 1 Cor 5:6-8.
  
  
• First Fruits (one day, start of Spring, shortly after Passover)  - This holiday celebrates the offering to God the first items from your garden each year. Rather than enjoying that first strawberry or other food you first see a few weeks after you've planted your garden, you are to think of God first and bring that food to give to Him in sacrifice, rather than prioritize your own hunger. Some have suggested that the reason God rejected Cain's offering of vegetables in Genesis 4 is because Cain brought the leftover vegetables instead of the first fruits (best quality fruits). If Passover is Good Friday when Jesus died, and then a few days later First-Fruits would be Resurrection Sunday. The New Testament speaks multiple times of the "first-fruits" being Jesus and the first converts to Christianity (Rom 8:23; 11:6; 1 Cor 15:20; 15:23; 2 Thess 2:13; James 1:18; Rev 14:4), with the promise of future/later fruits to come.
  
  
• Pentecost (one day, the 50th day after first-fruits) - The first-fruits refer to the first foods that come early in the growing season, while Pentecost signifies the more full harvest later on. We can easily see the need to honor God when the bulk of our food for the year has begun to all come ripe at the same time. If the first-fruits of Easter is the Resurrection of Jesus, then imagine the much bigger harvest that is yet to come, namely the descent of the Holy Spirit on Pentecost Sunday (Acts 2). If you thought Baptism was good, just wait till you get Confirmed and receive the Eucharist!
  
  
• Trumpets (one day, 7/1) - This holiday is seen as the close of harvest season, and hence the Jews see it as the first day of the new year, when another chapter of life beings. That would mean this feast of trumpets corresponds to the conclusion of salvation history, and ushering in a new era, when the end of the harvest has taken place and judgement has come. Trumpets can signify the coming of the King, as Paul notes the return of Jesus will be ushered in by a trumpet (1 Thess 4:16).
  
  
• Day of Atonement (one day, 7/10) - This day is when the high priest makes atonement for all the sins of the nation, and re-consecrates the people and the temple from all the defilement of the year. It is one of the only times the Jews were liturgically required to Fast, and thus would correspond to our Lenten Fast (supposed to be 40 days in traditional Christianity). The New Testament fulfillment of this Day of Atonement is obviously the Cross, that ultimate atonement, which takes away all of our sins (Heb 9:6-7).  
  
  
• Booths (seven days, 7/11-7/18) - This week long holiday is when the Israelites were to live in tents rather than inside their own house. This was to remind them that they didn't have a home while living in the desert in the Exodus. Obviously, living in a tent is not a fun thing to do long term, especially when you had less comforts than our modern day camping. The New Testament fulfillment of this is to remind us that this life isn't meant to be comfortable, and that we are transients, having no  stable home in this world (Heb 11:9). On the Mount Tabor when Jesus was transfigured, it seems this was during the Feast of Booths, but it is here where Jesus shows His earthly tent (Body) to be full of divinity.
  
  
• [Honorable Mention] Hanukkah (seven days, 9/25-9/31) - This holiday is not mentioned in Leviticus and not taught by Moses. This holiday came around 800 years after Moses, when the Jews in the Book of Maccabees recovered and reconsecrated the Temple from pagan desecration, and the Jewish lamps burned seven days without needing oil refilled. This corresponds to Jesus as "Light of the World" and the one who re-consecrates the desecrated Temple. John 10:22-23 tells us that Jesus celebrated this holiday.
  

It is crucial that Christians live according to a liturgical calendar, as this is foreshadowed in the Israelite practice, and even goes back to Genesis 1:14 when God created the sun, moon, and stars to help us discern the "appointed seasons" (this is a liturgical term in Hebrew). Numbers 28-29 is similar to Leviticus 23, but has more details given. In Numbers 28, it specifically calls out that the Israelites are to have daily sacrifices, weekly sacrifices (Saturday), beginning of each new month sacrifices (New Moon), then sacrifices on the major holidays mentioned above.

God obviously wants us to live on a cycle, as well as with various days, seasons, etc, scattered throughout. In fact, the main reason why many pagan philosophers and religions believed the world to be eternal was because the calendar repeated itself every year. The Israelite religion stood out from this by saying there was an initial Creation, specifically in the Seven Days narratives of Genesis 1-2, which helped the Israelites stand out from other religions and help the nations discern what was the True Religion. While some false religions held the world was eternal due to the calendar repeating itself, others held it came about through gods fighting or random mutations and clashing elements due to the evil and sin in the world. Only the Israelite religion put things straight: one supreme God created things good, and out of love, but things fell due to sin, and that God wants us to live on a cycle to suggest an eternal element, combined with start and stop days and unique/important days mixed in. It is a shame and very impoverished form of Christianity when many Protestants have thrown out holidays and liturgical calendar, reducing the religion to having few/no special days and thus no times to stop, fast, celebrate, and rest.