There is a Biblical Commandment to count the days between the Passover and Shavuot, the Feast of Weeks (a.k.a. Pentecost). We start counting on the second day of Passover (the first day of the barley harvest in the land of Israel, when the wave-offering of the omer, i.e., “sheaf,” of ripe barley was made in the Jerusalem Temple) and finish on the eve of Shavuot—the day when two loaves of bread made of wheat were offered at the Temple. There are exactly seven weeks (forty-nine days) between these two holidays; we are commanded to count the weeks and the days. These forty-nine days are called days of Sefirat HaOmer (the ays of “counting the Omer”) or simple days of Sefirah. This commandment is given in the following verses of the Torah:
And ye shall count unto you from the morrow after Shabbat, from the day that ye brought the sheaf of the waving; seven weeks shall there be complete; even unto the morrow after the seventh week shall ye number fifty days; and ye shall present a new meal-offering unto the Eternal…. And ye shall count unto you from the morrow after the Shabbat, from the day that ye brought the omer of the waving; seven weeks shall there be complete. (Leviticus 23:15-16,21)
Seven weeks shalt thou number unto thee; from the time the sickle is first put to the standing crop shalt thou begin to number seven weeks. (Deuteronomy 16:9)
(As we discussed previously in “Passover, Shabbat and the Principle of Least Action,” the word “Shabbat,” i.e., the “day of rest,” in these verses is a euphemism for the Passover.)
Thus, the Torah commands us to count seven weeks and “fifty” (actually, forty-nine) days. We find in the Talmud:
Abaye stated, “It is a Mitzvah to count the days, and it is a Mitzvah to count the weeks.” (Menachot 66a)
A tradition recounted in Midrash Rabbah, states that, when Jews left Egypt, Moses told them that G‑d would give them Torah on Mount Sinai forty-nine days later. People were so excited about receiving Torah that they counted each day in eager anticipation of this event. Accordingly, today the practice is to count both the days and the weeks. For example, on the eighteenth day of the omer, we would count thus: “Today is eighteen days, which is two weeks and three days of Omer.”
As the above sources indicate, there is a commandment to count both the seven weeks as well as the forty-nine days of which said weeks are comprised. This “double-counting,” however, begs for an explanation. Anybody with most rudimentary counting skills can calculate the number of weeks from the number of days and the number of days from the number of weeks. Why must we count both?
Physical v Spiritual
A day represents a physical phenomenon—a complete revolution of the earth about its axis, which takes approximately 24 hours. We see it with our own eyes as the cycle of day (light) and nite (darkness), as the apparent movement of the sun across the sky, and other physical phenomena caused by the inertial forces (e.g., Coriolis force) arising in a non-inertial frame of reference. Counting days, therefore, is counting our progress in the physical world.
On the other hand, there are no known physical phenomena associated with a week. It is a purely spiritual construct. We structure our lives around weeks because the Torah tells us that in the first six days, G‑d created the world, and on the seventh day, Shabbat, He rested. We are, therefore, instructed by G‑d to follow this seven-day cycle by working six days and resting on the Shabbat. Counting weeks, therefore, is counting our spiritual progress.
If, as described above, days describe physical phenomena and weeks describe a spiritual construct, our life in both of these time domains (we live in days by sleeping, waking, eating, working, etc.; we live in weeks working six days and resting on the seventh, i.e., by celebrating Shabbat every seventh day, which is accomplished by the fulfillment of a special set of mitzvot—DOs and DON’Ts) the juxtaposition of counting days and counting weeks means counting progress in both the physical as well as the spiritual domains.
Time: Linear v Cyclical
Different cultures and religions have different conceptions of time. Many ancient religions and cultures believed in cyclical time. This is very natural because we measure time using cyclical processes, such as the day-night cycle and planetary motions that create seasonal cycles. The cyclical notion of time, therefore, is very natural and intuitive. Many ancient Greeks philosophers, such as Orphics and Pythagoreans, believed in the cyclical nature of time and the “wheel of time.” Ancient Greeks were aware of the “Great Year,” a complete cycle of equinoxes, when all planets and stars return to their original positions. This happens every 25,800 years. Pythagoreans believed that at the end of each Great Year, time ends, and history repeats itself in an endless succession of such cycles. Although Plato believed that time was created by G‑d, he identified time with the cyclical motions of the planets. Indian Hindus and Buddhists, Mayans, and others also believed in the “wheel of time.” Roman Mithraists believed in a finite “Time of the Long Dimension,” which cyclically repeated itself every 12,000 years.
Judaism postulates the creation of the world and its ultimate redemption, with time marking progress towards redemption.
Other Abrahamic religions, i.e., Christianity and Islam, adopted the notion of redemption and, therefore, a belief in the progression of time from Creation to the Apocalypse. However, it seems that the notion of cyclical time no longer plays a prominent role in these religions.
By contrast, Judaism’s conception of time incorporates both notions—cyclical time and forward movement in time. Thus, the Jewish concept of time is akin to a complex spiral with multiple periods—days, months, years, Sabbatical cycles (Shmita), Jubilees (Yyovel),, and millennia (seven millennia constituting a cosmic Shmita) —where each cycle represents a step forward in time. The cyclical aspect of the Jewish calendar manifests itself primarily in the annual holidays, which not only commemorate historical events (such as the Exodus from Egypt on Passover or the Giving of the Torah on Shavuot) but, as Kabbalah teaches, reenact these events on a spiritual level every year. All these cycles—a day, a year, a Sabbatical, a Jubilee—not merely repeat themselves but add up in a constant progression towards the universal redemption.
This may be another reason why during the Sefirah period we count both weeks and days. A week represents a cycle, which repeats itself every seven days. Thus, counting weeks is a nod to the cyclical aspect of time. Counting days, on the other hand, is the acknowledgment of the forward movement—the progress—in time. The seemingly redundant combination of counting both days and weeks is a statement of our belief that that time has both aspects—forward-moving progression as well as the cyclical aspect—which are integrated into the spiral of time that moves the world towards its redemption.
Klal and Prat
One of the principal methods of Biblical hermeneutics is the dichotomy of klal (general) and prat (particular). Everything is analyzed on the level of minute details as well as how these details fit into the bigger picture. (See, for example, “Abel and Cain Conflict—Wave-Particle Duality and “Primordial Serpent—the Incurable Atomist.”)
In the context of the “double-counting” (weeks and days, respectively) of the Omer, weeks represent the klal aspect, whereas the days represent the prat aspect. We start with the recognition of the precept of counting seven full weeks between the Passover and Shavuot. This is the klal view. We then zoom in on every constituent day to make sure that the day is counted in a literal and metaphorical sense—we count the day and make our days count. This is the prat view. Having worked on and refined the individual days, we put them back together into weeks when we say, “Today is seven days—which is one week—of the Omer.”
Orot and Kelim
Some of the most important concepts in Kabbalah are Orot (“lights”) and Kelim (“vessels”). In Kabbalah, “light” is a metaphor for Divine emanation. Keli (singular of kelim), simply speaking, is something that holds that spiritual light, as a vessel would. Actually, a “vessel” is a spiritual information processing system—it received the “information” (i.e., the light or emanation) in, processes it (i.e., measures how much of this light can be passed on to the next level and how much must be retained), and outputs the measure of light such that the level immediately “below” (i.e., further removed from the source) can absorb and process. Another useful metaphor for a keli is a color glass. When the white light goes through a color glass, most of the spectrum is absorbed with only a narrow band of the spectrum representing the specific color of the glass being let through. Similarly, a keli absorbs (or holds) most of the light that shines into it, allowing only a small measure of this light to pass through.
Isaac Newton, as well as other philosophers before him who viewed time as objective reality, imagined time as a vessel filled with events. However, Newton maintained, even without any event, an empty vessel still exists. Thus, he thought, time would exist even in an empty universe.
As mentioned above, a week has no physical counterpart. No physical phenomenon is associated with a period of seven days. Thus, a week is not an event per se. Days, on the other hand, mark physical events—passing of one revolution of the earth around its axis after another. These events—days—fill a week, which is comprised of days, as they fill a container or a vessel—keli. We can say, therefore, that by counting weeks, we count kelim (vessels), whereas, by counting days, we count orot (lights).
Two Systems—the Tetragrammaton and the Sefirot
From the point of view of Kabbalah mysticism, the twenty-four-hour cycle of a day is due to twenty-four permutations of the letters of the Proper Name of G‑d known as the Tetragrammaton or Havaya (the “Eternal”). This name is called Tetragrammaton because it is made of four letters: Y-H-W-H. The number of all possible permutations of four letters is twenty-four. Each such permutation “rules” over the particular hour. We also note that only three of the four letters are unique (as the letter Heh is repeated twice). Thus, only twelve permutations are distinct. This is why, according to Kabbalah, the twenty-four-hour day is divided into two twelve-hour periods. Furthermore, Kabbalah teaches that the first Heh and the second Heh, albeit the same letter, represent different Partzufim. Therefore the first twelve-hour period and the second twelve-hour period differ in that one describes night hours and the other the day hours.
The seven-day cycle we call a week is related to another spiritual system—seven Divine Emmanatoins, midot, which we will discuss at a greater length below. Each day of the week is “ruled” by a particular midah.
There is a debate in the Talmud about what exerts a greater astrological influence on a child—the day of the week or the hour of the day on which the child was born.
It is possible to say that the daily and weekly counting of the omer is an acknowledgment of these two systems—one related to permutations of the letter of the Tetragrammaton and the other to the seven Divine Emmanatoins, midot.
Tohu and Tikun
Kabbalah teaches that the first created universe was Olam HaTohu (the Universe of Chaos). The emanations of the Infinite Light (Ohr Ein Sof) manifested themselves in this universe as ten distinct Sefirot (“emanations”). The lower seven Sefirot are called midot (“measures” or emotive attributes). These midot are Chesed (“kindness”), Gevurah (“strength,” “judgment”), Tiferet (“beauty,” “compassion”), Netzach (“victory,” “eternity”), Hod (“splendor”), Yesod (“foundation”), and Malchut (“kingship”). The midot of Tohu (as all of the Sefirot of Tohu) are solitary light—they do not interact with each other—each stands on its own.
The other created universe was Olam HaTikun (the Universe of Rectification). In this universe, all sefirot are inter-included—each sefirah contains all ten sefirot. Based on that fractal nesting (See, “Fractal Patterns in the Torah”), there are forty-nine combinations of midot:
|1: Chesed of Chesed
|2: Gevurah of Chesed
|3: Tiferet of Chesed
|4: Netzach of Chesed
|5: Hod of Chesed
|6: Yesod of Chesed
|7: Malchut of Chesed
|8: Chesed of Gevurah
|9: Gevurah of Gevurah
|10: Tiferet of Gevurah
|11: Netzach of Gevurah
|12: Hod of Gevurah
|13: Yesod of Gevurah
|14: Malchut of Gevurah
|15: Chesed of Tiferet
|16: Gevurah of Tiferet
|17: Tiferet of Tiferet
|18: Netzach of Tiferet
|19: Hod of Tiferet
|20: Yesod of Tiferet
|21: Malchut of Tiferet
|22: Chesed of Netzach
|23: Gevurah of Netzach
|24: Tiferet of Netzach
|25: Netzach of Netzach
|26: Hod of Netzach
|27: Yesod of Netzach
|28: Malchut of Netzach
|29: Chesed of Hod
|30: Gevurah of Hod
|31: Tiferet of Hod
|32: Netzach of Hod
|33: Hod of Hod
|34: Yesod of Hod
|35: Malchut of Hod
|36: Chesed of Yesod
|37: Gevurah of Yesod
|38: Tiferet of Yesod
|39: Netzach of Yesod
|40: Hod of Yesod
|41: Yesod of Yesod
|42: Malchut of Yesod
|43: Chesed of Malchut
|44: Gevurah of Malchut
|45: Tiferet of Malchut
|46: Netzach of Malchut
|47: Hod of Malchut
|48: Yesod of Malchut
|49: Malchut of Malchut
It is these forty-nine permutations of midot that we count during forty-nine days of Omer. Prayers recited on each of the forty-nine days of Omer name that day’s specific combination of midot, invoking special meditations related to the specific combination.
A week, which has seven unique days, may be seen as a reference to the seven distinct midot of Tohu. The forty-nine days, however, represent forty-nine combinations of inter-included midot as they exist in the Universe of Tikun. Perhaps one of the reasons we count both weeks and days is that weeks represent the rectification of the midot of Tohu, whereas days represent the inter-included midot of Tikun.
Passover means “to pass over”—a reference to Jewish houses passed over by G‑d during the plague of firstborns in Egypt. The Hebrew original, Pesach, means something similar—to “skip”—also a reference to the Jewish houses skipped by G‑d during the plague. The Hebrew original has a much deeper meaning as it also refers to “skipping” spiritual levels.
The Kabbalah teaches that, on the one hand, there are fifty “Gates of Wisdom,” referring to fifty levels of holiness, and, on the other hand, there are fifty gates of spiritual impurity. The sages tell us that spiritually, Egypt was the lowest place on earth—the fiftieth gate of impurity. Living in Egypt and adopting many of the Egyptian customs, the Jewish people fell to the penultimate level of impurity—the forty-ninth gate. They were not worthy of redemption. Nevertheless, G‑d pulled His children from the depth of the impurity in one fell swoop. Instead of climbing the ladder of spiritual ascent one rung at a time, the Jews skipped all the rungs—all levels of holiness—and were pulled out of the spiritual abyss of Egypt. This is why, according to Kabbalah, the holiday on which we celebrate the Exodus from Egypt, is called Pesach, i.e., to “skip”—because we skipped forty-nine levels of impurity. What we celebrate during the Passover is the quantum leap. Skipping levels is a characteristic feature of the holiday.
Passover is a holiday that has a twin holiday, Sukkot, symmetrically positioned on the timeline, precisely six months from the Passover. Sukkot also lasts seven days, like Passover. However, Sukkot is immediately followed by Shemini Atzeret—the Holiday of the Eighth Day. Although it is considered the last day(s) of Sukkot, technically, it is a separate holiday. Why does the Passover not have a symmetrical Holiday of the Eighth Day? It actually does—it is Shavuot. Indeed, in the Mishnah, Shavuot is also called Atzeret. It is detached, however, from the Passover by the forty-nine days of sefirah. Why?
Technical traders know a rule—when a stock leaps suddenly to a much higher price than usual, it will have to recede to its average value and then, level by level, climb to the new high. So too here. Having skipped the forty-nine levels during the Exodus from Egypt, the Children of Israel had to now climb the forty-nine steps of the spiritual ladder leading to Mount Sinai, one rung at a time. Therefore, notwithstanding this slight detachment and delay, in the Chasidic tradition, Shavuot is considered the conclusion of Passover, just as Shemini Atzeret is the conclusion of Sukkot.
When the Torah commands us to count seven weeks from Passover to Shavuot, it tells us that Shavuot and the Giving of the Torah are seven “miles” (weeks) away. However, just as every mile is made of feet, every week is made of days. Thus, we begin to count day after day until we cover the complete seven weeks.
From this point of view, the counting of the weeks is a reference to skipping levels on Passover, and counting days is a reference to the methodic self-improvement and day-by-day spiritual ascent required to receive the Torah.
This concept is beautifully summed up by Henry Thoreau, who wrote:
If you have built castles in the air
Your word need not be lost;
That is where they should be.
Now put the foundations under them!
― Henry David Thoreau, Walden
 Although the verse in Leviticus states 50 days, the Rabbis of the Talmud explain this to mean forty-nine days. See Tosafot Kasuv Echad on Menachot 65b, Rashi on Leviticus 23:16. (Some authorities say we do, in fact, count 50 days, with Kiddush on Shavuos being the 50th counting.)
 The way we count weeks is we say, “Today is so many weeks and so many days of Omer.” For example, today is two week and four dadys of the Omer. So all one needs to do is to multiply the number of weeks by seven and add the reminder number of days, to get the full count of the days of the Omer.
 Coriolis force is an inertial force (similar to the centrifugal force) that acts on objects moving in a rotating frame of reference. In a reference frame that is rotating clockwise, the force acts to the left of the moving object. In a reference frame that is rotating counterclockwise, the force acts to the right of the moving object. The resultant change of the trajectory of the moving object is called the Coriolis effect. This force was mathematically described by the French physicist Gaspard-Gustave de Coriolis in 1835. Coriolis effect plays an important role in meteorology and is responsible for the rotation of large cyclones. The Coriolis effect also explains why river banks in the northern hemisphere erode their right-hand banks more than their left-hand banks—the phenomenon known in geography as the Baer–Babinet law.
 Because the earth is rotating around its axis it is a non-inertial frame of reference.
 The reason creation took seven days (with G‑d “working” for six days and “resting” on the seventh), and the subsequent week-cycle being similarly structured, is based on the structure of the sefirot and, specifically, the lower seven sefirot called the seven midot. Each day of the creation is identified in Kabbalah with the corresponding midah in the World of Atzilut (the “World of Emanation” and the higher world in the chain of ontological realms called Seder Hishtalshelut). For example, the first day of creation is the Chesed of Atzilut, the sixth day of creation is Yesod of Atzilut, and the Shabbat of Creation is Malchut of Atzilut.
 The Sabbatical cycle repeats itself every seven years (akin to seven days of the week) with the seventh year being the Sabbatical year (Shmita) when all loans are forgiven.
 Jubilee is a fifty year-cycle with the fiftieth year (Yovel, or “Jubilee”) occurring after the completion of the seven Sabbatical cycles (Shemitah). All ancestral property was returned to the original owners and slaves were released on Jubilee.
 Cosmic Sabbatical cycle (or Cosmic Shmita) is a seven thousand-year cycle corresponding to the seven-day cycle of the week. According to the Jewish tradition, the world will exist for six thousand years corresponding to the six days of Creation followed by the thousand years of Messianic kingdom corresponding to the first Shabbat of Creation. According to great Tana and Kabbalist Rabbi Nehunya ben HaKana (the assumed author of the Book of Bahir), the world will exist seven such Cosmic Sabbatical cycles—forty-nine thousand years in total. As interpreted by the medieval Kabbalist Rabbi Isaac of Ako, these refer’s to G‑d’s days, which amount to about fifteen billion earthly years.
 This notion of absolute time was strenuously opposed by Leibnitz, who saw time and space as relative.
 Partzuf (plural partzufim) is a dynamic spiritual construct that is comprised of inter-included sefirot in the Universe of Tikun (there are no partzufim in Tohu). Originating in Zohar, the word partzuf is alternatively translated as Divine “visage,” “face,” “personae,” “form,” or “sefirotic configuration.” In the Lurianic Kabbalah, there are six primary partzufim: Atik Yomin (the “Ancient of Days”; the primary sefirah is the inner dimention of Keter, as it includes all ten sub-sefirot, signifying the Divine Pleasure, ta’anug), Arich Anpin (the “Long Face” or Macroprosopus; the primary sefirah is the external dimention of Keter, as it includes all ten sub-sefirot, signifying the Divine Will, rotzon), Aba (the “Father”; the primary sefirah is Chokhmah, as it includes all ten sub-sefirot, signifying the Divine Wisdom and the Male Principle), Imma (the “Mother”; the primary sefirah is Binah, as it includes all ten sub-sefirot, signifying the Divine Understanding and the Female Principle), Zeer Anpin usually abbreviated as the Z”A (the “Small Face” or “Microprosopus”; comprised of six midot—Chesed, Gevurah, Tiferet, Netzach, and Hod , as each of them includes all ten sub-sefirot, signifying the Divine emotive attributes and the minor Male Principle); and Nukva (“Female” companion of the Z”A; the primary sefirah is Malchut, as it includes all ten sub-sefirot, signifying the Shechinah—the Divine Presense or minor Female Principle). All anthropomorphic designations are not to be understood literal, but purely allegorical. Interactions of the partzufim, particularly the coupling of partzufim, are seen as responsible for all spiritual dynamics of Seder Hishtalshelut. Four partzufim—Aba, Imma, Z”A, and Nukvah—correspond to four letters of the Tetragrammaton and to the four worls of the Seder Hishtalshelut, in which the respective partzuf “nests.”
 Ultimately, Talmud rejects astrological influences on the Jewish people. As Rabbi Yochanan argues: Ein Mazal L’Yisrael—“there is no star for Israel.” (Shabbat 156a-b, Nedarim 32a; see also Bereishit Rabbah 44:12)
 Perhaps it’s a bit of a stretch, but one might say that the “double-counting” of the omer is a veiled hint to two Messiahs—Mashiach ben Yosef (Messiah son of Joseph) and Mashiach ben David (Messiah son of Joseph). As I wrote in my essay, “Joseph and His Brothers,” Judah, the progenitor of Mashiach ben David is connected to the decimal system of numbers manifesting in ten sefirot. Joseph, on the other hand, was connected to the duodecimal number system based on the number 12. Midot are merely a subset of the Ten Sefirot. Consequently, we can say that counting weeks, which is connected with the midot (lower seven sefirot), is connected with Judah and, ultimately with Mashiach ben David. Counting days, on the other hand, connected to the 24-hour cycle based on the permutations of the Tetragrammaton is connected to the duodecimal system of counting (because it is really two periods of 12 hours), which ultimately hints at Mashiach ben Yosef. According to tradition, Mashiach ben Yosef will arrive first waging wars against the enemies of the Jewish people. He will be killed in the battle. Mashiach ben David will arrive after him, completing the unfinished task of liberating the land of Israel and reestablishing the Davidic dynasty.
 See Simon Jacobson, “Counting of the Omer.” New York: Meaningful Life Center, 5th edition (1996).
 According to the Kabbalah, G‑d created the world zeh l’uma zeh, i.e., “this opposite of that.” This means the domain of spiritual impurity was created opposite to—and a mirror image of—the domain of holiness. The physical parallel of this being matter and antimatter. Just as there are ten Sefirot of holiness, there are ten crowns of impurity. And just as there Fifty Gates of Wisdom, there are fifty gates of impurity.
 In Israel, Shemini Atzeret is celebrated one day, whereas, in Diaspora, it is celebrated two days, the second day of which is Simchat Torah.
 Mishnah, Rosh HaShanah 16a; Talmud, Pesachim 68b. See also Targum to Bamidbar 28:26.
 Counting of forty-nine days of Omer may be viewed as us connecting Shavuot to the Passover, making sure the latter will not be left without its proper conclusion, it’s Atzeret, as it were.
 In Kabbalah, the annual succession of Holidays is seen as various stages of maturation of the mentality of the partzuf Zeer Anpin (Z”A) and its Nukvah. Skipping spiritual levels on Pesach parallels skipping levels of maturation of the Z”A, which emerges during the Passover with immature mentality. The following forty-nine days of counting Sefirat HaOmer are days of maturation of the mentality of the Z”A.