Hello Rabbi Haber, I hope you are doing well. I understand what you explained regarding Rabbi Eliezer being more motivated to derive Mashiv Haruach U'Morid Hageshem from Lulav if Nisuch Hamayim isn;t on the first day because if it indeed was on the first day, then he would derive it from Nisuch Hamayim because it's more directly related to water( as supposed to Lulav which is indirectly related). What I don't understand is why Rabbi Eliezer wants the hazkara to be mentioned on day one specifically! I understand on Amud aleph Tosafot said that Rabbi Eliezer holds one must לרצות לפני שאלה and he is not Makpid on Siman Klala like Rabbi Yehoshua but why day 1? why not day 2? why is he so determined to find a source to derive that Mashiv Haruch U'Morid Hageshem is to be said on the first day? Doesn't it usually work that something motivates you to want it to be a certain way? Thank you Rabbi for your time!

<p class="MsoNormal" style="margin-bottom: 10.0pt; line-height: 115%;">Yasher koach for taking the time out to listen to my presentation of this Tosfos.&nbsp; <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">ברוך ד' שכוונתי</span> to your &nbsp;insightful question which I spent some time contemplating <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">בשעתו</span> and searching for answers in the <span dir="RTL" lang="HE">מפרשים</span>.&nbsp; Since, unfortunately, we do not have <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">תוספות הרא"ש</span> or other parallel <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">תוספות</span> on <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">תענית</span>, it&rsquo;s harder to research questions on Tosfos in Ta&rsquo;anis.</p> <p class="MsoNormal" style="margin-bottom: 10.0pt; line-height: 115%;">A proposed answer to your question: In general, any time a Tanna or Amora presents a halacha and then brings a proof from a passuk/Torah concept one can analyze what came first &ndash; the <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">סברא</span> or the <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">דרשה</span>?&nbsp; In other words, did he &ndash; based on other aspects of Torah &ndash; theorize a certain halacha and then sought to <u>verify</u> it or find a support via <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">דרשות</span> OR did he enter the topic without any preconceived <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">סברות</span>, allowing the <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">דרשות</span> to <u>generate</u> the halacha?&nbsp; This is debated between <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">חכמי ישראל</span> &ndash; see for example &ldquo;The Dynamics of Dispute&rdquo; by Rabbi Zvi Lampel <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">)</span>p. 22 ff. and the endnotes to Chapter 1).&nbsp; I humbly suggest that both models could be true applying each one to different statements.&nbsp; Certainly regarding <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">דינים דרבנן</span> such as the starting day of <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">הזכרת גבורות גשמים</span>, the passuk support is just an <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">אסמכתא</span> or parallel Torah concept and does not generate the halacha.&nbsp; There, the view of <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">סברא</span> generating the halacha and then looking for Torah parallels is even more compelling since it is not the <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">דרשה</span> which generates the &nbsp;<span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">דין דרבנן</span> &ndash; otherwise it would be <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">מן התורה</span>!</p> <p class="MsoNormal" style="margin-bottom: 10.0pt; line-height: 115%;">In light of all of the above, we can suggest that R. Eliezer views <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">הזכרת גבורות גשמים</span> on the <u>first</u> day of Sukkos as logically compelling.&nbsp; It is logical to do the <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">ריצוי</span> during the entire Yom Tov, starting from the first day, before asking for rain <u>after</u> the Yom Tov.&nbsp; But then R. Eliezer seeks a Torah parallel.&nbsp; Once found, since <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">כל דתקון רבנן כעין דאורייתא תיקון</span> &ndash; all Rabbinic laws follow Torah precedents, we would follow the details of that Torah law applying them to the <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">דין דרבנן</span> which was initially ordained independently.&nbsp; In this particular case, this would mean starting <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">הזכרת גשמים</span> at night if following the <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">ניסוך המים</span> model and during the day if following the <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">לולב</span> model.&nbsp; Tosfos seem to maintain that if both models are available because <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">ניסוך המים</span> also starts on day one, then that model is preferable, as pointed out by <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">מאירי</span> and <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">חזון איש</span>, since it is more directly related to water.&nbsp;&nbsp; But if <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">ניסוך המים</span> is on day 2, the <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">סברא</span> of starting on day 1 will &ldquo;win out,&rdquo; and we will use the less ideal parallel of <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">לולב</span> following its day precedent.</p> <p class="MsoNormal" style="margin-bottom: 10.0pt; line-height: 115%;">R. Yehuda b. Beseira and R. Akiva, on the other hand, do not enter the discussion from a preconceived <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">סברא</span> of <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">הזכרת גבורות גשמים</span> starting on the first day of Yom Tov since regardless there will still be some <span dir="RTL" lang="HE">ריצוי</span> before the request for rain.&nbsp; Therefore, they allow the more intuitive parallel of <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">ניסוך המים</span> &ndash; being more directly connected to water &ndash; to inform their start date for <span dir="RTL" lang="HE" style="font-family: 'Arial',sans-serif;">הזכרת גבורות גשמים</span>, whether day 2 or day 6.</p>