When Isaac was old, his eyes grew too dim to see (Genesis 27:1).
Isaac’s blindness—the first infirmity mentioned in Scripture—sets the stage for deception and for two brothers’ struggle over a birthright and a blessing. For one ancient sage, Isaac’s blindness not only begins one story but it continues and deepens the traumatic story of Isaac’s near death at his father’s hand—a horror that remained with him, always:
When Isaac was old, his eyes grew too dim to see. (Genesis 27:1) Literally, the verse reads: And it was that Isaac grew old and his eyes grew dim from seeing. The unnamed sage teaches that Isaac was scarred by what he and the terrified angels had seen, his eyes weakened…by the power of that sight; for at the hour that Abraham, our Father, bound his son on top of the altar, the ministering angels cried. And those tears fell from their eyes into Isaac’s eyes and they left traces in his eyes, as it is written: And it was that Isaac grew old and his eyes grew dim from seeing. (Click here for the midrash)
The sage has an ally in the Israeli poet, Hayim Gouri:
He lived a long life,
saw the good, until his eyes dimmed.
But that hour he bequeathed to his descendants.
They are born
with a knife in their hearts.
(Click here for the entire poem in Hebrew and English)
The phrase, as the story is told, can ring with assurance or with skepticism. The ancient sage secures his insight regarding Isaac’s traumatized life to the story of his weak eyes precisely, literally, as the story is told in the verse: his eyes grew weak from seeing.
The poet, on the other hand, is skeptical that the nearly sacrificed Isaac could have lived a normal life: As the story is told, Isaac was not sacrificed. But the poet does not believe it. In some sense, Isaac was sacrificed, his life forfeited. As the story is told, Isaac saw the good, until his eyes dimmed. But how much goodness could Isaac have seen and appreciated from that hour onward until his eyes dimmed?
Not only did Isaac carry that sight all of his life, but it became the legacy of his descendants—as the story is told by the sage and by the poet.
Sicha - Continuing the Conversation 
Perhaps both poem and midrash point to the possibility that Isaac’s vision was “darkened” from having “seen too much” long before the literal, physical blindness that can come with age set in. And it’s easy to consider the possibility that his resulting dim view of life was passed on to his descendants, in one form or another.
Quite insightful (pun intended) – I only wish our guest speaker was coming the following weekend. I will place this in my Toldot file for next year.
Yishar Kochecha
The poet exceeds his license. In the story, as well as in the poem, the knife is referred to as a maachelet. This is a very special kind of knife used for killing something to be eaten, from the root ochel.
Abraham nor his descendants are cannibals. It is the land that eats its people, as the spies tell us. The lesson is that we are not to be consumed by the land. Nor are we to worship it; for that would be idolatry. The knife and land are a means to an end, to make it and ourselves holy=korban, close to God. This cannot be done through hatred.
Don Goldstein
I read “with a knife in their hearts” as the wounding image it must be—just as we would say “a knife in the back” is a wounding image…but the heart, besides being the most vulnerable site in the body, is also the seat of individual will (does b’libam in hebrew connote this also? ). So the heart is now in possession of the weapon and the violence that goes with it. The knife, along with the will to wound/sacrifice another– is also the legacy.
Hello! Very interesting angle, we were talking about the same thing at work and found your site very stimulating. So felt compelled to comment and thank you for all your effort. Please keep up the great work you are doing!