It was taught: Rebbi Eliezer says that the world was created in Tishrei and the forefathers (Avraham, Yitzchak and Yaakov) were also born in Tishrei.... Rebbi Yehoshua says that the world was created in Nisan and the forefathers were also born in Nisan....

Their views here are consistent with their opinions in another matter, for it was taught: "In the second month, on the 17th of the month, in the 600th year of Noach's life, on this day all the wells of the deep burst forth..." (Bereishit 7:11) -- Rebbi Yehoshua says this refers to the 17th of Iyyar (the second month counting from Nisan).... Rebbi Eliezer says it was the 17th of Marcheshvan (the second month from Tishrei)....

The conclusion of the sages of Israel was to reckon the chronology of the Flood according to Rebbi Eliezer's opinion, but to use the opinion of Rebbi Yehoshua when it comes to calculating the times of the Tekufot (= the beginnings of the seasons -- the equinoxes and solstices).

(Rosh Hashanah 10b-12a)

Whose opinion is accepted in this dispute? The Gemara tells us that when it comes to dating the Flood, Rebbi Eliezer's opinion is followed. As Rashi (ad loc.) points out, this implies that Rebbi Eliezer's opinion is accepted when it comes to the chronology of Creation. This is why we add a year to our count of the number of years since Creation on every first of Tishrei (i.e. Rosh Hashana).

On the other hand, the Gemara tells us, such is not the case when it comes to calculating the "Tekufot." The Tekufot (s. "Tekufah"), or the equinoxes and solstices, are determined according to Rebbi Yehoshua's opinion that the world was created in Nisan. We assume the in year #1 the sun was placed in the sky on the eve of Wednesday (the 4th day of creation) at the beginning of Nisan. That moment is assumed to be the first vernal equinox in history. We predict equinoxes and solstices, and arrange the lunar year to be consistent with them, by assuming that a new equinox or solstice will occur every 91 days and 7 1/2 hours (or 55/48 minutes less than that, according to Rav Adda's later emendation of the Jewish calendar) since that first Wednesday in Nisan. We do *not* start our calculations from the eve of Wednesday in the beginning of the following Tishrei.

It would appear that this "compromise" is completely self-contradictory. If the world was created in Nisan, as Rebbi Yehoshua claims, how can we calculate the dates of Creation and the Flood from Tishrei; and if it was created in Tishrei, as Rebbi Eliezer says, how can the Halacha tell us to base our astronomic calculations on the assumption of a Nisan Creation?

The Rishonim (early commentators) deal with this paradox in several different ways.

The reason we consider Tishrei to be the beginning of a new year, they explain, is only because Tishrei starts a new year in either case for several other Halachic purposes. As the opening Mishna in Rosh Hashana tells us, Tishrei is the beginning of the agricultural tithing cycle, the beginning of the Shemittah and Jubilee years, etc. (see Parasha-Page, Rosh Hashana 5756, section 1). Since 1 Tishrei is considered to be the Rosh Hashanah (the beginning of the year) for these other Halachic issues, it is appropriate to consider it the beginning of a new year as far as *numbering* the years as well. After all, the day upon which we add 1 to the previous count of the years need not be the actual date of Creation. It will suffice even if it is an arbitrary date, established by convention.

We might add a further justification for our system of counting a new year on 1 Tishrei, based on the opinion of Rabbenu Tam (see Parasha Page for Rosh Hashanah 5756, Part III). Rabbenu Tam (in Tosafot to Rosh Hashanah 27a) explains that Hashem originally "decided" to create the world in Tishrei, although He did not actually do so until Nisan. 1 Tishrei can be said to be the date that the world was "conceived" -- the beginning of the beginning. If so, this would indeed make 1 Tishrei an appropriate day with which to start our count, even though the world wasn't actually created on that day.

What does the Ran mean by this? His answer does not seem to address the question at all! The computation of the Tekufot is based on the fact that the sun was placed in the heavens and began its first cycle on a Tuesday night/Wednesday eve at the beginning of either Nisan or Tishrei, depending on when the world was created. A certain number of days and hours is added to that moment for each successive seasonal cycle since then, and that is how the present-day Tekufot are reckoned. Of what significance is it that Nisan is a nice time to start off the seasonal cycle? What do aesthetics have to do with this calculation? If the sun was created in Tishrei, then making computations based on Nisan will be *incorrect*!

(3) The words of a Tosafot elsewhere in Rosh Hashana compound the problem of following Rebbi Eliezer for some matters and Rebbi Yehoshua for others. Tosafot (Rosh Hashana 8b, s.v. Le'Tekufot, towards the end) presents us with a variant reading of the Talmud's conclusion in regard to the month of Creation. According to his reading, the month that begins a new year-count is not discussed. Rather, what the Gemara concludes is that the Halacha is in accordance with Rebbi Eliezer with regard to establishing the times of the Molad, i.e. for determining the start of the *lunar* cycle upon which our calendar is based (we have a tradition that the first Molad took place at the beginning of the fifteenth hour of the sixth day of Creation - Tosafot ibid.). At the same time, however, the Halacha accepts Rebbi Yehoshua's opinion when it comes to the Tekufot, i.e. for determining when the *solar* cycle begins. (Tosafot's reading has its basis in the words of Rabbenu Channanel to Rosh Hashana 12a.) Here we have two astronomical calculations, which are clearly both dependent on establishing a date for creation. Yet, according to Tosafot's variant reading, the Gemara splits the two issues, favoring R. Yehoshua's opinion in one and R. Eliezer's in the other. As the Rashash (Vilna ~1850) points out, such a Halachic ruling would seem unjustifiable!

A further, more basic question may be asked concerning this whole discussion. How can there be any doubt as to which calculation of the equinoxes is correct? It is a simple matter to measure which day of the year was the equinox, post facto. By calculating backwards in time, we should be able to derive easily whether the sun's cycle started, 5756 years ago, on a Wednesday in the beginning of Nisan or on a Wednesday in the beginning of Tishrei! How can this point be a matter of controversy?

This answers why the dispute between Rebbi Eliezer and Rebbi Yehoshua was not settled by observation. Astronomically, the two opinions are identical. If the Sages would have worked the Tekufah calculations according to Rebbi Eliezer's opinion, they would have started with a sun that was created in middle of a cycle, and arrived at the same conclusion as far as today's Tekufot are concerned.

Now that we have shown that the actual calculation of the Tekufot is not dependent on the date of the Creation, we can understand how the Ran can claim that it is more "auspicious" to begin our Tekufah calculations from Nisan:

The Sages accepted Rebbi Eliezer's view, that the world was created in Tishrei. When it comes to Tekufah calculations, however, they determine where the sun *would have been* in the Nisan that preceded the Tishrei of Creation, and proceed to divide the days between that time and the present into 91.3125 parts, using the remainder to predict the time that the next Tekufah will begin. This is what they meant when they said that the Halacha is in accordance with Rebbi Yehoshua as far as the Tekufot are concerned. Why didn't the Sages determine in which part of the Tekufah the sun was when it was *actually* created, in Tishrei, and then divide the days that passed since then into 91.3125 to find when the sun will next reach that same point in a Tekufah? The simple answer is that it is more practical to provide a calculation that will yield a time for the *beginning* of future Tekufot, and not for the middle of those Tekufot.

What, then, does the Ran mean when he states that the Sages count Tekufot from Nisan because in Nisan trees begin to blossom and the sun brings forth new growth? Perhaps he is providing an explanation for why Hashem created the sun in the middle of a cycle, according to Rebbi Eliezer, rather than at the start of a cycle. Hashem created the sun such that it would have started a cycle on the eve of a Wednesday in the preceding Nisan, for that is a more appropriate time to "begin" the sun's yearly series of four seasons! (NOTE: The Gaon's presentation of the Ran's intention differs slightly from the one I present here. I've oversimplified it somewhat.)

We can also explain the variant reading of Tosafot now, adds the Gaon. Since there is a tradition that the first Molad was at the ninth hour of the sixth day of creation, the calculation of the Molads must be computed based on the date of the sixth day of creation. There is no tradition, however, that the sun began a cycle upon its creation. To the contrary, according to Rebbi Eliezer it must have been created in the *middle* of a cycle, as we have explained above. The Gemara rules in favor of R. Eliezer, that Creation was in Tishrei, and the reckoning of future Molads is made from that first Tishrei accordingly. However, when it comes to computing the Tekufot, it makes no difference that the world was created in Tishrei!

(More explanation is in order, if we also wish to explain how we make the Birkat HaChama in Nisan. Birkat HaChama is a blessing that we make once every 28 years, when the Tekufah of Nisan (= the vernal equinox) comes out at the start of a Tuesday evening. It commemorates the creation of the sun, since the sun was created at the beginning of a Tuesday evening that coincided with the vernal equinox (Rashi Berachot 59b). Why do we make this blessing in Nisan, according to the Ran who contends that the world was not created in Nisan but in Tishrei? It was on a Wednesday that the Tekufah of *Tishrei*, (= the autumnal equinox) if anything, originally began. What event of Nisan are we commemorating?

We must apply a variation of the Gaon's reasoning here too. Even if we accept the opinion of R. Eliezer that the world was created in Tishrei, the autumnal equinox did not occur on that evening. An equinox would, however, have begun on the eve of Wednesday six months earlier, in Nisan, and it is therefore that cycle that we are commemorating with Birkat HaChama.)

PUZZLE

Who would like to try to work out whether the Tekufah, according to the calculations used in the Jewish calendar, would have actually started on the beginning of Wednesday eve, 5756 1/2 years ago? When would be the next closest year that the Tekufah of *Tishrei* would actually start on a Wednesday? And was the Molad of Tishrei 5756 years ago really on 1 Tishrei, at the very beginning of the fifteenth hour from nightfall? What day in the lunar calendar coincided with the equinoxes in the year of creation?

HINT: The Jewish calendar recognizes September 5th and March 5th to be, respectively, the autumnal (Tishrei) and vernal (Nisan) equinoxes. Assume, for the sake of simplicity, that the solar year consists of exactly 365 1/4 days, and each season is 91 days and 7 1/2 hours long. Therefore the Tekufah of Nisan must always occur on March 5th at the beginning of one of the four quarters of the day: at the start of the day or the night, or at midday or midnight (Eruvin 56a). As for the lunar cycle, we calculate the time from Molad to Molad as 29 1/2 days, and 793/1080th of an hour. A recent Molad was on October 24th 1995, 4:29 AM plus 15/18th's of a minute. If you can't figure that in your head, perhaps you'd like to try it with a calculator after Shabbat!

ALTERNATE HINT: The autumnal (Tishrei) and vernal (Nisan) equinoxes are, respectively, Sept. 20 and March 20. Assume that the moment of the equinox moves up exactly 1/4 day every year, thus returning to the beginning of the evening with every fourth (leap) year (Eruvin 56a). Since there are 7 days in a week, every 4x7=28 years, the equinox returns to the beginning of a Tuesday evening. The lunar calendar is identical in relation to the solar calendar, every 19 years (i.e. 1 Tishrei will be the same day on the solar calendar every 19 years).