Parashat Vayera tells of the miraculous birth of Yitzchak, when his parents were, respectively, one hundred and ninety years of age.
It is commonly assumed that the name “Yitzchak” has to do with either Avraham’s response of “laughter” (or “joy”) upon learning that Sara would bear him a son (“va-yitzchak” – 17:17), or Sara’s remark upon her son’s birth, “kol ha-shomei’a yitzechak li” (“everyone who hears will rejoice for me” – 21:6). The Midrash (Bereishit Rabba 53:11), however, comments, somewhat ambiguously, that the name “Yitzchak” represents the phrase, “yatza chok le-olam” – “A law went forth into the world.”
Rav Menachem Bentzion Zaks, in his work Menachem Tziyon, explains this to mean that the circumstances surrounding Yitzchak’s birth will be characteristic of the unusual pattern of Am Yisrael’s survival. The “law” that “went forth into the world” at the time of Yitzchak’s birth was that Avraham’s legacy would endure and flourish even when it appears that it has reached the end of its line. Sara’s inability to conceive was looked upon as foreboding the quick demise of Avraham’s teachings. Without a child to perpetuate his legacy, his success would soon fall into the ashbin of history. As Avraham and Sara gradually entered old age, it became a foregone conclusion that their legacy was short-lived. This perception changed, of course, with the birth of Yitzchak.
This, the Menachem Tziyon explained, is the “law” that came into being with this event. At various points in Jewish history, our spiritual tradition reached the brink of extinction, as the older generation began shrinking while the younger generation felt alienated and eager to leave their ancestral heritage behind them. But just as Yitzchak miraculously came into the world to perpetuate the legacy of Avraham, similarly, Torah tradition has somehow always managed to survive against all odds. This is the chok, the “law” that cannot be explained in natural terms, that was established with the birth of Yitzchak.