(א) שָׁמוֹר֙ אֶת־חֹ֣דֶשׁ הָאָבִ֔יב וְעָשִׂ֣יתָ פֶּ֔סַח לַיהֹוָ֖ה אֱלֹהֶ֑יךָ כִּ֞י בְּחֹ֣דֶשׁ הָֽאָבִ֗יב הוֹצִ֨יאֲךָ֜ יְהֹוָ֧ה אֱלֹהֶ֛יךָ מִמִּצְרַ֖יִם לָֽיְלָה׃
(1) Observe the month of Abib and offer a passover sacrifice to your God יהוה, for it was in the month of Abib, at night, that your God יהוה freed you from Egypt.
(31) Now [during the plague of hail] the flax and barley were ruined, for the barley was in the ear and the flax was in bud;
We can see that Aviv is actually a reference to the crop of barley, which is sown in the Spring. So the very source of the name of the month is the crop identified with that month.

(1) THIS MONTH SHALL BE UNTO YOU THE BEGINNING OF MONTHS.
Now the purport of the expression, This month shall be unto you the beginning of months, is that Israel is to count this as the first of the months, and from it they are to count all months — second, third, etc., until a year of twelve months is completed — in order that there be through this enumeration a remembrance of the great miracle, [i.e., the exodus from Egypt, which occurred in the first month]. Whenever we will mention the months, the miracle will be remembered. Thus everytime a person says, for example, “the third month,” he implies that it is the third in the order of the months which begins with Nisan, when the exodus occurred. It is for this reason that the months have no individual names in the Torah.
Akkadian |
Hebrew |
Nisanu |
Nissan |
Aru |
Iyar |
Simanu |
Sivan |
Dumuzu |
Tammuz |
Abu |
Av |
Ululu |
Elul |
Tisritum |
Tishrei |
Samnu |
Cheshvan |
Kislimu |
Kislev |
Tebetum |
Tevet |
Sabatu |
Shevat |
Addaru |
Adar I |
Addaru Arku |
Adar II |
Month |
Length |
Nissan |
30 days |
Iyar |
29 days |
Sivan |
30 days |
Tammuz |
29 days |
Av |
30 days |
Elul |
29 days |
Tishri |
30 days |
Heshvan |
29 or 30 days |
Kislev |
30 or 29 days |
Tevet |
29 days |
Shevat |
30 days |
Adar |
29 or 30 days |
Adar II (Leap years only) |
29 days |
Why is Adar always the leap month? Because it is the month that precedes Nisan, the birth of our nation. This is a way of emphasizing the coming of Nisan.
Rabbi Yitz Greenberg
What makes a day holy? Who creates an obligation to say prayers on a certain day, or to march around with a lulav and etrog, or to stay up all night studying Torah? You might think that God imbues each holy day with a special texture since, after all, God’s commandments determine the special behaviors which we follow. But the Rabbis’ answer is: Judaism is a covenant-partnership in which the human partner plays a central—even authoritative—role. It is the earthly court which decides that Yom Kippur will occur on Tuesday, not Wednesday, thereby endowing that tenth day of Tishrei with sacred character requiring life-altering behaviors and extended prayers. Their decision creates the 24 hours of special closeness to God when the Shekhinah is nigh and receptive to human repentance and piety.
§ Rabbi Shimon ben Pazi raises a contradiction between two verses. It is written: “And God made the two great lights” (Genesis 1:16), and it is also written in the same verse: “The greater light to rule the day, and the lesser light to rule the night,” indicating that only one was great. Rabbi Shimon ben Pazi explains: When God first created the sun and the moon, they were equally bright. Then, the moon said before the Holy One, Blessed be He: Master of the Universe, is it possible for two kings to serve with one crown? One of us must be subservient to the other. God therefore said to her, i.e., the moon: If so, go and diminish yourself. She said before Him: Master of the Universe, since I said a correct observation before You, must I diminish myself? God said to her: As compensation, go and rule both during the day along with the sun and during the night. She said to Him: What is the greatness of shining alongside the sun? What use is a candle in the middle of the day? God said to her: Go; let the Jewish people count the days and years with you, and this will be your greatness. She said to Him: But the Jewish people will count with the sun as well, as it is impossible that they will not count seasons with it, ...... God saw that the moon was not comforted. The Holy One, Blessed be He, said: Bring atonement for me, since I diminished the moon.
The Slonimer Rebbe on the Meaning of the Full Moon, (Derived from R. Miriam Margles):
The Slonimer Rebbe frames the symbolism of the moon in the context of the Jewish people. At the most general level, he says that the history of the Jewish people has been like the moon: long periods of darkness and gloom, most of their days in exile, suffering greatly. But, even at the deepest darkness they know that soon they will shine once again as before. He expands on this in several ways. Rabbi Miriam Margles draws from the teachings of the Slonimer’ (who she refers to as R. Shalom Noach, to distinguish him from the previous Rebbes of the Slonim dynasty) to draw several lessons of more universal application from his teaching:
1) The new moon is not visible. There is a darkness and absence between moon cycles. Between endings and beginnings there is often a void. And into that void, we often pour our anxieties, uncertainties, aches and isolation. R. Shalom Noach identifies the blessing and celebration of rosh chodesh (the new moon) as training us to be present with the darkness of a moonless moment and to bring trust and blessing to the darkness.
2) The dark-night celebration of the new and concealed moon also teaches us to view ourselves through its wisdom. R. Shalom Noach states, “Only the blessed Holy One sees our innermost innerness, where there is no stain.” The Divine force can bless and celebrate in us what we may not be able to perceive in ourselves. We are like the dark side of the moon when we are keenly aware of our failings and faults, but do not see the inherent goodness that may be obscured but is still ever-present. The new moon encourages us to see ourselves through the eyes of love, conscious of the one who loves us despite all the ways we mess up and cause harm.
3) The moon teaches that the capacity for renewal is constant, and so we are guided to continually engage in renewing ourselves. The moon’s constant changing teaches that we are not limited by who we were yesterday. This is the power of teshuvah. The new cannot arise out of what is familiar and fully known. We need to bring ourselves to the darkness with a sense that it is the seed and source of renewal. The first mitzvah, contradicting enslavement, is to be in this state of vulnerability, available to to perpetual change, to evolve, to be alive.