Haamek Davar to Vayera 18:12 (and, to a lesser extent, the surrounding verses) and Harchev Davar (by the same author) to Vayera 21:3 explain Sarah's laughter on learning that she and Abraham would have Isaac. (See 18:9–15 and 20:2 – 21:2 for the context.) As well as I can understand it, he explains as follows (but I'm including only the parts relevant to my question).
Sarah did not doubt that she could become pregnant. God, as she knew well, can do anything. However, she became youthful again and Abraham did not. That, coupled with the pledge that they would bear a son, made her wonder at God's plan: did He plan to have the child born through natural means, as her newfound youth would imply, or through miraculous means, as Abraham's old age would imply? This oddity made her laugh.
Now, paralleling Isaac's birth is the provision of sustenance to Jewry for generations to come. Indeed, that provision is based on divine attention to our deeds, which is supernatural, but its proximate cause is our hishtadlus, practical effort at making a living, which is natural. Analogously, the initial cause of Isaac's birth was Abraham's siring him, which was supernatural because Abraham was too old to father a child, but the proximate cause was Sarah's motherhood, which was natural due to her youth.
That miraculous cause of Isaac's birth was doubted by other nations (who suspected that Abimelech had fathered Isaac) until, over time, they came to acknowledge it due to Abraham's also fathering Keturah's sons; likewise, the miraculous origin of our sustenance is doubted by the other nations until, over time, they will come to acknowledge it due to our merits' also providing non-Jewish peoples' sustenance.
For this reason, Isaac's name Yitzchak is mentioned in Midrash Raba as alluding to yetze/yatza chok, "food will/did go out" to the world: because Isaac is an allusion to sustenance of the world.
Now, compare — this is still the Harchev Davar — Ⅰ Chronicles 16 with Psalms 105. The former says "Remember His covenant forever!… that He struck with Abraham, and His oath to Yitzchak". The latter says "He has remembered His covenant forever… that He struck with Abraham, and his oath to Yischak". (The latter form of Isaac's name signifies laughter and merriment but not yetze/yatza chok, sustenance.) The covenant is the covenant of circumcision, which has two aspects to it (expanded on in 17:13): that a circumcision, namely a letting of blood, be done, and that the foreskin not cover the circumcision site. That the foreskin not cover the site is what marks us visibly as Jews, and thus allows gentiles to pain us; Psalms says God remembers that and alludes to the merriment coming to us to balance out the gentiles' paining us. Chronicles, on the other hand, refers to the letting of the blood, which, like the blood of an altar sacrifice, provides merit for sustenance (alluded to by the name Yitzchak); thus, although we forget, as adults, the pain of the circumcision, we're told to remember the circumcision.
I have three questions.
- He says that Sarah was punished for her laughter. Why? If her laughter was at the novelty of God's acting through natural means and simultaneously through supernatural means (see especially Haamek Davar to 18:12!), why is that laughter deserving of punishment?
- I don't understand why it's we who should remember the blood-letting aspect of circumcision and the sustenance that that provides, but God who says He'll remember the foreskin's not covering the circumcision site. It seems just as reasonable to say (rewording my above paraphrase): "That the foreskin not cover the site is what marks us visibly as Jews, and thus allows gentiles to pain us; Psalms says we should remember that and alludes to the merriment coming to us to balance out the gentiles' paining us. Chronicles, on the other hand, refers to the letting of the blood, which, like the blood of an altar sacrifice, provides merit for sustenance (alluded to by the name Yitzchak); thus, although we forget, as adults, the pain of the circumcision, God remembers the circumcision." but that's not what he says. Why not? What's the connection between who remembers and the rest of the explanation of those verses?
- At the end of the Harchev Davar to 21:3, he notes that we read about the birth of Isaac on Rosh Hashanah nowadays but did not do so while the Temple was standing in Jerusalem (see Bavli M'gila 30–31), and says that this is because "the causation of our sustenance is relevant only nowadays in our diaspora". How do we understand this, or why is it so? He had previously given examples of how God's plan for our sustenance (predicated on supernatural intervention, caused proximately by our efforts, and affecting all the world) was in place even while the Temple was standing, and gave our offering seventy bulls on Tabernacles as a part of this system. So why does he now say that "the causation of our sustenance is relevant only nowadays in our diaspora"?