I srael's Declaration of Independence pledged "absolute equality of social and political rights to all its inhabitants, irrespective of religion, race or sex". This pledge was surely derived from the age-old Jewish idea that all human beings are created equal. But, to this day, it has never been enshrined in Israeli law.

A scribal error in the Talmud sheds new light on this anomaly and highlights the gap between authentic Jewish thought, modern Jewish practice and today's human rights agendas. The text in question re-examines the biblical account of the creation of mankind and asks, "Why was the human race formed from the offspring of a single person?"

It gives three answers. First, to teach that someone who saves a single life earns the merit of saving an entire world, ie the value of a single life is infinite.

Second, for the sake of peace, so that no-one should be able to say, "My father was more important than your father".

Finally, so that every individual should be able to think, "For my sake the world was created".

Although these words pre-date modern campaigners by nearly 2,000 years, they provide a more compelling manifesto for universal rights than any current political agenda. Every activist should know them.

But most activists, and most members of modern Jewish communities, will never see them. For the quotation above is missing from my edition (Mishnah Sanhedrin, 4:5). It appears in almost all the reliable early manuscripts. It is quoted verbatim by Maimonides and by the Meiri, the medieval Talmud commentator. It is quoted in the Koran.

However, it does not appear in modern printed editions of the Talmud. Instead, today's editions say "someone who saves a single Jewish life earns the merit of saving an entire world".

The word "Jewish" turns the vision and meaning of the Mishnah upside-down. If only a Jewish life is worth an entire world, then perhaps a non-Jewish life has different value. Perhaps, to misquote Thomas Jefferson, "not all men are created equal".

Most modern editions do not acknowledge the existence of the original text even in a footnote. Kahati, the most widely-read modern commentator, is silent. So is Artscroll, the publisher of a major new commentary on the Talmud. Albeck, who prints the word "Jewish", agrees that manuscripts which leave out this word are "correct". But he places this admission in an obscure appendix where few will see it. With the exception of Steinsalz, who also prints the word "Jewish" but mentions the original text in a note at the side of the page, the authentic reading has been lost.

How did this happen? The first dated occurrence of the word "Jewish" in the text is in the Firenze manuscript of the Talmud, from the end of the 12th century. Then it is a minority reading: none of the contemporary manuscripts of the Mishnah include it and it is unknown to the contemporary commentators. The context in which the Mishnah is writing - that of Adam and Eve - refers to mankind in general rather than to the Jewish people in particular.

Neither does the word "Jewish" appear in the first two printed editions of the Mishnah. Only in the third edition, Bomberg's Babylonian Talmud, the first-ever printing of the entire Talmud, does the word "Jewish" appear. And after that point it never vanishes, copied from one printed edition to another in a continuous line to the present day.

Could Bomberg have selected the reading of the Firenze manuscript deliberately when he printed his Babylonian Talmud? Probably not. His printing of the Jerusalem Talmud (based on the Leiden manuscript) retains a different reading of the Mishnah without the word "Jewish". Most likely, he followed whatever manuscripts happened to come to his hand.

Of course, there could have been an element of choice, if not by Bomberg, then by others. The first five centuries of the last millennium were centuries that began with the Crusades and ended with the expulsion of Jews from Spain and Portugal. Jews were persecuted and slaughtered across Europe. It is no surprise that some manuscripts voted against the idea that Jewish and non-Jewish life holds equal value.

But now? Across almost all the Western world Jews enjoy equal rights with non-Jews. Nearly 2,000 years after the Mishnah's composition, Western countries appear finally to have learned its authentic teaching.

Shall the Jewish community, the community that invented the idea that "all people are created equal" be the only community to teach its children and grandchildren that some are more equal than others? And shall the pledges of the Declaration of Independence wait unfulfilled another year?

Benedict Roth studied Talmud at Israel's Pardes Institute