It is a common scene on many a Saturday morning in cities and towns across the United States to see seventh- and eighth-grade boys and girls, a few not Jewish at all, gather in synagogues and temples to watch a classmate’s bar mitzvah.

This coming-of-age ritual marks a 13-year-old man’s assumption of religious and legal obligations under Jewish law.

In my experience, many modern-day teens who gather for this ceremony have no idea what the word bar mitzvah means, nor how the ceremony they have come to observe evolved.

Early practice and history

The roots of the bar mitzvah, which literally means “son of the commandments,” are obscure. The term never once appears in the Hebrew Bible.

Ancient rabbis, writing in the compendium of Jewish law known as the Talmud, did declare that boys are obligated to fulfill the “mitzvot” – the commandments of Jewish law – beginning at the age of 13. But as an historian of Judaism, I know that rabbis and commentators have struggled with the question of why the age of 13 was actually chosen.

After some debate, these Jewish scholars concluded by the 11th century that it must have been an orally transmitted requirement handed down to Moses when he stood atop Mount Sinai. There, Moses received not just the Ten Commandments but also, according to Jewish tradition, all Jewish law, both written and spoken.

The first use of bar mitzvah for the Jewish coming-of-age ritual seems to date to a 15th-century rabbi named Menahem Ziyyoni.

The bar mitzvah ceremony at that time was a modest affair with two or three major components. First, was an “aliyah.” This meant that the bar mitzvah boy was, for the very first time in his life, called up to make a blessing over the public readings from the Torah, the sacred handwritten scroll containing the Five Books of Moses. In addition, the bar mitzvah boy often delivered his first public “discourse,” teaching the community and offering thanks to his parents and visiting guests.

Modern-day bar mitzvah

The bar mitzvah boy, however, was not expected to read from the Torah, chant the Prophetic portion associated with it, known as the Haftarah, or lead any part of the prayer service, as so many do today.

Those elements came later, in the 18th and 19th centuries, when the bar mitzvah grew in importance for the Jewish communities of Europe, North America and the Caribbean. As traditional Jewish communal authority weakened during the Enlightenment period, newly emancipated Jews across the globe became citizens with civil and political rights.

Anxious parents wondered whether their sons would carry on ancestral traditions such as observing Jewish law, studying Jewish texts, marrying within the faith and raising their own children Jewish. The more they worried, the more they focused on the bar mitzvah – the last religious rite of passage they could control.

By the early 20th century, many bar mitzvah boys publicly pledged “to love, honor and keep the Holy Torah.” The 20th century also witnessed the spread of a parallel ceremony for girls, known as the bat mitzvah, meaning “daughter of the commandments.”

In lands where Jewish life was changing rapidly, families seemingly sought to stave off fears of the morrow. Parents strove, at least momentarily, perhaps for one fine Saturday morning, to reassure themselves and the community that Jewish learning and life would continue despite the lure of modernity and its many seductions.

[ Deep knowledge, daily. Sign up for The Conversation’s newsletter. ]

Jonathan D. Sarna does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.