Volume 22 Number 11
                       Produced: Mon Nov 20 23:50:15 1995

Subjects Discussed In This Issue: 

Jewish Calendar
         [Mottel Gutnick]
         [Ari Shapiro]


From: Mottel Gutnick <MOTTEL@...>
Date: Fri, 17 Nov 1995 17:34:12 GMT+1000
Subject: Jewish Calendar

Following an article of mine on the Calendar in v21/#94 (Digest 370), I
was asked by Steve White in v21/#97 (Digest 371) to comment on what,
exactly, constitutes [keeping] Pesach in season.

I have decided to respond by enclosing, below, an extract on precisely
this topic, from a paper I am writing on the Jewish Calendar. Please
note that, although it is not published, the paper is copyright and
therefore, although the extract may be freely quoted for purposes of
discussion, it may not be otherwise disseminated without permission and

I apologise for its length, but the subject is a complex one and, faced
with the choice of being brief but cryptic or long but, I hope, lucid, I
opted for the latter. I hope it is not too tedious. Critical comment is

I should like to ask readers one thing in particular. The material below
touches on the question of whether Pesach may commence on the day of the
(computed) spring equinox. As pointed out in my last article, "computed"
must be taken, in the context of our present Calendar, as computed in
accordance with the tropical-year length of Rav Adda Bar Ahava, namely,
365d 5h 997ch 48reg (where 1h=1080ch and 1ch=76reg). However, whilst I
have seen instructions as to how to calculate the tekufot (the computed
equinoctial and solsticial days of the calendar) according to Mar Shmuel
(whose year length is 365.25d), I do not know the procedure for
calculating them according to Rav Adda.

Even if the same procedure is to be followed as for calculating the
tekufot according to Shmuel, but with an appropriate adjustment for the
difference in year length, it seems to me that we still need a base date
from which to count. That is, a date on which a tekufah (any tekufah) is
known to have occurred according to Rav Adda, or, more specifically,
according to our current fixed calendar which was, as I established in
my previous article, founded upon Rav Adda's calculations.

If anyone can help with this, please respond. I would like to ascertain,
by such a calculation, whether, in our current calendar, Pesach has ever
commenced, or can ever commence, on the day of the computed spring
equinox (or, for that matter, whether it ever precedes the equinox,
although I very much doubt that that is possible, as will be seen from
the material below). One thing is clear (I think): it is a mistake to
assume that we can use, for this purpose, the equinoxes and solstices as
calculated by modern astronomical ephemera or almanacs, since they are
probably not calculated exactly the same way that Rav Adda would have

The extract below does not deal with all the four questions Steve White
raised, only with the first one. Readers will notice, however, that the
last paragraph of the extract leads directly towards a discussion of
Steve's questions 2 and 3, and similar matters arising from my previous
article, but, given the length of this posting, I thought it better to
leave a discussion of those for next time.

----- (extract commences) -----

The intercalary month is always inserted before Nisan. Thus, whenever
an intercalation occurs, the month that would ordinarily have been
called Nisan had there been no intercalation is now called Adar II,
and Nisan will be the month following Adar II. This was to ensure that
Pesach would never precede the equinox and would thus always occur in
its correct season--something that the Torah was most anxious to
ensure. [3]

-- (the footnote, below, comprises the entire remainder of this article)


[3] Deuteronomy 16.1a introduces instructions regarding the Pesach
sacrifice and its associated festival, with the words "Observe the month
('chodesh') Aviv". According to Rabbinic interpretation, (T.B., R.Hash.
21a) this signifies an instruction to "see to it that the Aviv SEASON
[i.e. spring] occurs during the new part of Nisan [the lunar-MONTH
Aviv]." The "new part" means the first half of the month -- the period
during which the moon is still growing. According to this
interpretation, this is implied in the verse by the word "chodesh", a
derivation of chadash (new) -- the import, here, of "chodesh" being the
'newness' of the month. (Rashi on Talmud, loc. cit.)

The Talmud (loc. cit.) records that Rav Huna Bar Avin sent to Rava the
following instruction guiding him as to when a leap year must occur.
"When you see [by calculation] that the season of Tevet [i.e. winter]
extends up to the sixteenth of Nisan, make that year a leap year
[i.e. intercalate an extra Adar] ..." (After this follows a parenthetic
remark which need not concern us here.) He then concludes by citing the
above verse and asserting the aforementioned interpretation in support
of his rule.

Now the equinoctial and solsticial days of the calendar mark the
commencement, in each case, of a new season. This rule is in accordance
with R. Jose's opinion recorded in Sanh. 13a, and was established, says
Rashi here in R.Hash., in contradistinction to R. Judah's view (ibid)
that they mark the last day of the outgoing season. This should be borne
in mind when analysing Rav Huna's instruction, as we are about to do.

Rashi interprets Rav Huna's instruction as a rule that the calendar must
be so arranged -- either by means of intercalation or by another method,
to be described presently -- as to ensure that the (computed) spring
equinox will occur during or, in a leap year, before, but never later
than the new half of Nisan, which he takes as meaning the first fourteen
days of the month, during which the moon is still growing. Thus, Nisan
15 must never precede the equinox.

We may conclude from this that the requirement to keep Pesach in season
means, specifically, that: (a) it may not commence before the day of the
(computed) spring equinox, the day on which the spring season commences,
and (b) it should commence, if possible, in the same calendar month in
which the equinox occurs, or, at the latest, in the following month. (In
a common year, Pesach will occur in the same month as the equinox,
whilst in a leap year, when the equinox occurs in the second half of
Adar II, Pesach will occur in the next month.)

In other words, Pesach must commence at the time of the full moon that
occurs on, or next after the (computed) spring equinox.

Wording the rule in this (second) way immediately brings to mind the
question of what should happen in the borderline case where, without
intercalation, the (computed) equinox would occur on Nisan 15 itself. In
other words, are we justified in including the words "on, or" in the
second wording above of the rule regarding the commencement of Pesach? I
do not know whether our present, fixed calendar, allows this, but it is
this possibility, under the old calendar, which is at the centre of the
differing interpretations offered by Rashi and the Tosafot of Rav Huna's
instruction to Rava.

A careful reading of Rashi's interpretation given above will reveal
that, according to Rashi, we do not allow this to occur. But, he says,
there is no need, in such a case, to intercalate an extra month to
prevent this from occurring because an alternative remedy is available:
extend Adar from twenty nine to thirty days, thus postponing Nisan 15 to
the day after the equinox. Therefore, according to Rashi, this situation
does not come under Rav Huna's rule.

A careful reading of Rav Huna's words tends to support Rashi's
interpretation, the wording being "intercalate the year when winter
extends UP TO Nisan 16." That is to say, we must certainly intercalate
the year if winter extends so far as to include the sixteenth (i.e. when
spring commences on the seventeenth or later) -- of that there is no
question. But, says Rashi, we intercalate the year [even] if winter
extends only UP TO, but NOT [necessarily] inclusive of, the sixteenth.
For if spring commences on the sixteenth we still have no choice but to
intercalate the year, because to extend Adar in such a case would only
succeed in changing the date of the equinox from the sixteenth to the
fifteenth, which, according to Rashi, is of no avail. Thus, by this
reading of Rav Huna's words, he is specifically defining the limiting
case -- i.e. intercalate when the equinox occurs on, or after, Nisan 16,
but not if it occurs before. For if it commences the day before, we can,
by merely extending Adar, change the date of the equinox from the
fifteenth to the fourteenth.

In the Tosafot, a view opposite to that of Rashi is taken on the
question of whether Pesach may commence on the day of the equinox
itself. (The author is not named but Rabbi Steinzaltz writes that the
view expressed is that of Rabbeinu Tam and that it is also shared by a
majority of commentators, namely, RaSHBA, ROSH and RaN). The author
refers to a dictum in Sanh. 41b which puts the latest time for the
blessing of the new moon at the fifteenth of the month, from which he
infers that the fifteenth is also regarded as falling within the new
part of the month.

Consequently, he argues, if the spring equinox occurs, by computation,
on Nisan 15, we need not take any steps to prevent this. Therefore, in
their reading of Rav Huna's instruction to intercalate the year when
winter extends up to Nisan 16, the Tosafot are forced to interpret the
words "up to" as signifying up to, AND INCLUSIVE of the sixteenth. That
is to say, on this reading of Rav Huna's words, his instruction applies
only when spring commences on or after the seventeenth, for if it
commences the day before, on the sixteenth, the alternative remedy of
extending Adar to thirty days would suffice to change the date of the
equinox from the sixteenth to the fifteenth, upon which, in the Tosafist
view, it is permitted to fall. Alternatively, says our Tosafist, Rav
Huna's words can be interpreted to mean: intercalate when winter would
extend up to [but not necessarily inclusive of] the sixteenth, even if
we were to intervene by extending Adar. Both interpretations amount to
the same thing (i.e. the same rule would apply); they differ only in the
meanings, both of which are somewhat forced, that must be attached to
Rav Huna's words in order to accomodate the view of the Tosafot.

This opinion would support the inclusion of the words "on, or" in the
rule formulated above as to the commencement of Pesach, namely, that it
must commence at the time of the new moon on, or next after, the
(computed) spring equinox.

Let us now use the letter N to designate the last day of the new part of
the month, recognising that the Tosafot are in dispute with Rashi as to
whether N equals fifteen or fourteen. We may now say, in summary, that
in consequence of this dispute they differ as to whether we allow the
(computed) spring equinox to occur on the fifteenth of Nisan and, hence,
to coincide with the commencement of Pesach (this being the Tosafot's
view), or whether we must intervene to prevent this (this being Rashi's

At any rate, leaving aside their dispute as to the value of N, both
Rashi and the Tosafot are in agreement that when the equinox is computed
to occur, without intervention, on Nisan N+1, the method of intervention
that we apply is to extend Adar from twenty nine to thirty days, rather
than intercalating the year, which we are forced to resort to if the
equinox occurs any later. It should be noted, in connection with this,
that they both seem to assume, since nothing is said to the contrary,
that it would be possible to extend Adar for this purpose irrespective
of whether the new moon is sighted on the night after Adar 29. (A
sighting on that night would normally cause the next day to be
proclaimed as Rosh Chodesh Nisan, leaving Adar with only twenty nine
days.) They apparently believe that if such a sighting is reported, the
testimony may be suppressed or discounted if we need to extend Adar for
the abovementioned purpose. (A fuller understanding of the implication
of this may be gained after reading the section entitled "History.")

Note that whilst this remedy could postpone the nominal date of the full
moon according to the calendar (i.e. the fifteenth) and, hence, Pesach,
to the day after the equinox (according to Rashi) or the day of the
equinox (according to Tosafot), it could have no effect on the true moon
of the heavens. If, in fact, the new moon was sighted on the night after
Adar 29 and, ignoring this, we nevertheless extended Adar to thirty days
on account of the equinox, Pesach would then commence on the day after
the true full moon. Yet, despite this legal fiction, as it were, they
seem to prefer this method of intervention, where it will suffice, over
the prospect of intercalating the year.

>From the wording of Rashi, he, at any rate, certainly seems to favour
this method. This lends additional weight to our conclusion, reached
above, that, whilst the commencement of Pesach must never precede the
day of the (computed) equinox, it must also occur as close to the
equinox as possible -- hence, the wording of our rule that Pesach must
commence at the time of the full moon on, or NEXT after, the equinox.
(This will be of some significance when we consider what correction, if
any, will need to be made to our calendar in the far distant future to
compensate for its slight overestimation of the length of a tropical

----- (end of extract) -----

More will follow next time, hopefully, on the matter raised in the
last paragraph, above.

Mottel Gutnick, Melbourne Australia      <mottel@...>


From: <m-as4153@...> (Ari Shapiro)
Date: Thu, 16 Nov 95 09:24:31 EST
Subject: Zmanin

Important Note: When I say R' Tam I do not necessarily mean R' Tam
himself, I mean those Rishonim who hold like him.  Note: MIL in this
context means a measurement of time. Tzeis means when the stars come out
and alos means daybreak (sometime before sunrise).  Plag hamincha is
10.75 hours of the day

I would like to clarify one point. The crux of the argument that R' Tam's 
opinion (that night is 4 mil after sunset) has to also hold that a mil is 
22.5 minutes and that you have to count the hours of the day from alos 
until tzeis is the following.

1) The Rishonim who hold like R' Tam (Rashba Berachos 2a, Ritva Berachos 
3a, Ramban Toras Haadam etc.) all say that Plag Hamincha (10.75 hour of
the day) refers to Tzeis Hacochavim (when the stars come out) not
sunset meaning that plag hamincha is 1.25 hours before tzeis.

2) The Rishonim also say that Plag Hamincha is 1/6 of a MIL before sunset

3) Based on the above statements it is impossible to count the hours of the
day from sunrise to sunset, there aren't enough hours in the day. Here is 
an example. Sunrise is 6:00am sunset is 6:00 PM. If you would hold a mil is
18 minutes then Tzeis would be 7:12. Counting from sunrise (since that is 
when we start figuring out the hours of the day) Chatzos (midday)
is 12:00 Mincha Ketana is 12:30 Mincha gedola is 3:30 and Plag hamincha is
4:45. (10.75 hours of the day from 6:00 AM is 4:45) However 4:45 is 2:27
before Tzeis while Plag is supposed to be 1:15 before Tzeis (because Plag
is 1:15 before night which is Tzeis). There just aren't enough hours in the

4) If you count the hours from Alos until Tzeis (with a mil being 18
minutes) each hour is 72 minutes. Therefore Plag hamincha would be 5:42 
(1.25 hours before night and each hour is 72 minutes = 90 minutes)
however this is not 1/6 of a mil (3 minutes before sunset, therefore by 2
above this is not true.

However if a mil is 22.5 minutes and we count from Alos until Tzeis we 
get the following: An hour = 75 minutes (15 hours divided by 12). Tzeis is 
7:30 (4 mil = 90 minutes) plag is 5:56.25 (93.75 minutes before tzeis) 
which is 3.75 minutes before sunset which is 1/6 of 22.5. We see that the 
statements of the Rishonim work out perfectly.

IMPORTANT NOTE: This whole approach is based on the statements of the
majority of the Rishonim (Rashba, Ritva, Ramban, Raah) who hold that night
is 4 mil after sunset. R' Tam himself may not hold like this, but that is
irrelevant because all the Rishonim who hold this view state that Plag is
1/6 of a mil before sunset (and therefore a MIL has to be 22.5 minutes). 

If someone thinks you can hold that night is 4 mil after sunset and hold
a mil is 18 minutes and/or holds you count the hours of the day from
sunrise until sunset please provide a timeline of the various times and
how they work out with the statements of the Rishonim (in particular
when Plag Hamincha is).

Ari Shapiro


End of Volume 22 Issue 11