A haunting midrash cited by Rashi's commentary to this verse traces the origins of Isaac's blindness to the Akedah. At the moment when Abraham was about to sacrifice his bound son, the ministering angels witnessed the scene and wept. Their tears fell on Isaac's eyes, weakening them in his later life. This midrash might be read metaphorically. The tears of the angels represent the overwhelming experience undergone by Isaac on the altar. It was so intense that from that moment, Isaac never again lived fully in this world. When the Torah reports his passing in Genesis 35:28, it records simply that "the days of Isaac were 180 years". In reporting the deaths of both Abraham and Jacob, the Torah adds that they lived.

As many commentators have noted, Isaac is passive throughout his life. Other people act upon him or on his behalf; his few initiatives merely echo those of his father. Isaac's radical unworldliness, or other-worldliness, is reflected too in his unique holiness. Alone among the patriarchs, he is forbidden to leave the Holy Land, "for you were a pure offering", explains another midrashic passage, "and the rest of the world is not appropriate for you".

We are often told: "Judaism teaches that one should live in this world". Like most declarations beginning "Judaism teaches", this is one-sided and misleading. There is indeed a powerful strand in our tradition encouraging full participation in the world within the parameters defined by the Torah, sanctifying the mundane and bringing heaven down to earth. This is a compelling approach for many contemporary Jews.

But we should not forget that many fine Jews during some periods in our history followed an alternative traditional path, characterised by a more detached spirituality. Our rich heritage allows for disciples of Isaac as well as for followers of Abraham and Jacob.