Noted Torah scholar ACGAC (=a certain gan-age child) had the following to say about Parshat Vayeira*:
“The three malachim (angels) told Avraham that they were going to have a baby. They didn’t tell Sarah, but she heard, and so she laughed.”
Why did she laugh?
“Because they were already big, and they were already a saba (grandfather) and a savta (grandmother), and usually, they don’t have babies anymore.”
And so there you have it.
The miracle that even the Midrashim don’t tell you about is that Avraham and Sarah were apparently grandparents way before they had any children…
שבת שלום ומבורך!
* Since I established a precedent by posting a dvar Torah on Parshat Mikeitz the week of Parshat Vayechi, I figured I might as well post a quote from Shabbat Parshat Vayeira on Erev Shabbat Parshat Shmot… :-)