Mr. Wertheimer's sententious nonsense about the great Rosa Luxemburg and her demise had me about ready to send my laptop windmilling across the room. Had Luxemburg been a Jewish Bundist agitating for social democracy, would her death have been such a cosmic gotcha to the present defender of the faith? Her noble expression of a universal concern for all human suffering is dismissed here as famous last words, when in fact it is Mr. Wertheimer who suffers from a terminal naivete that the attitudes of the 19th century ghetto should or can be reaffirmed in the 21st century. (While we're on the subject of Cassandras, Luxemburg prophesied the disaster of Bolshevism far better than Mr. Wertheimer understands the historical Stalinist designation of "rootless cosmopolitans," who were alternatively known as Zionists, Titoists, Trotskyists, and CIA agents -- very often all of those things at once.)

If I were at all superstitious I might wonder about reading this extremely nervous screed on the same night I happened to glance at the population geneticist Spencer Wells's essay in Vanity Fair. Dr. Wells has argued persuasively that a mapping of our DNA proves humankind began in Africa and that we are all "African under the skin." So much for taking care of one's "family." For my own part, I would not want to belong to any nuclear unit whose patriarch spoke of the urgent need to stop the genocide of black Muslims in Darfur as "apple pie talk." Don't wait up for me next seder, Uncle Jack.

The scientifically proven truth of a biomolecular brotherhood of man is much more fulfilling and optimistic than any of the medieval hysteria passing for wisdom in this installment of the dialogue.

Mr. Wertheimer is right about one thing, however. People should be better versed in the cultural and religious traditions of Judaism, the better to decide for themselves just how alien and remote people from their own heritage can seem.