The wedding service used by Meghan Markle and Prince Harry at the royal wedding on Saturday is an old one. Many of its phrases, which date back to the original 16th century Book of Common Prayer, will be familiar to wedding-goers from all of the world: “dearly beloved,” “forever hold his peace,” “as long as you both shall live.”

But in other ways, the words spoken by the Prince and Markle — who was baptized and confirmed in the Church of England in preparation for the wedding — are decidedly modern. And one of those tweaks to tradition is likely to drawn particular attention: Markle’s decision not to promise to “obey” her new husband. Instead, Markle and Prince Harry each declared that they would love, comfort, honor, protect and be faithful to the other, and then vowed to have, to hold, to love and to cherish.

However, the new royal’s choice not to promise to obey Prince Harry isn’t exactly groundbreaking. That change to the traditional verbiage has evolved over the course of many decades, building on a service that has changed in many other ways too.

So where does the evolution begin? The Church of England split from Roman Catholicism in the 16th century, during the English Reformation. English history before that point included many different ways of solemnizing a marriage, from the Catholic mass to the more casual medieval practice of merely announcing consent to be married to traditional Anglo-Saxon-origin wedding vows, which today sound both familiar and rather colorful. In that wedding, the bride would promise to take her new husband, “to have and to hold, from this day forward, for better for worse, for richer and poorer, in sickness and health, to be bonny and buxom, in bed and at board, till death do us part.” (As the Telegraph has pointed out, “bonny and buxom” at the time would have meant “good and obedient.”)

It wasn’t until 1753 that English law first required that marriage take place with a Church of England minister in order to count (a law that held until the 19th century), but marriage in a church was common before then. For example, the Salisbury Cathedral in particular left an outsize imprint on the way pre-Reformation Roman Catholic Britons prayed, shaping what’s known as the Sarum Rite or Sarum Use — the Salisbury method of worship. The 1549 Book of Common Prayer that was developed during the Reformation used the Sarum Rite as one of its sources, including for the wedding service.

In the original Book of Common Prayer, the vows for the wife are slightly different than those for the man: he promises to love, comfort, honor and keep her; she promises to love, honor and keep, but also to obey and serve. That prayer book influenced many other English-language Church services, so those phrases pop up all over the place.

As liturgical studies expert Bryan Spinks wrote in a 1981 article on marriage in the Church of England, wedding services within the Church of England have long been basically just revisions of the 16th century Book of Common Prayer wedding, at least until a more radical experimental liturgy was introduced as an option in the 1970s.

But even so, as the liturgy remained fairly stable, “obey” was an early recipient of more minor tweaks.

In 1928 — just two years after British women were first allowed to own property the same way that men were — an attempted revision to the Church of England marriage service left out the “obey.” The 1977 revision did too. More recently, the Church of England Archbishops’ Council has formally acknowledged problems with the “obey” wording; in 2006, the Council published a report on domestic violence that noted that the promise was part of “standards or expectations of women and men within marriage” that were problematic and outdated.

But just because some Church of England congregants might haven chosen to skip “obey” almost a century ago, that doesn’t mean the royals did the same.

When Queen Elizabeth married Prince Philip in 1947, there had been some public debate over whether a future Queen ought to be promising to obey anyone. But she decided that regardless of her role as Queen, her role as wife would be traditional. As TIME noted in its 1947 coverage of the marriage:

Remembered too will be the silvered sounding of trumpets, the great beat of the Abbey organ, and the belling voice of Canterbury saying: ‘Philip, wilt thou have this woman,’ and ‘Elizabeth Alexandra Mary, wilt thou have this man,’ and the girl’s response, ‘to love, cherish, and to obey,’ audible only to those nearest in the Abbey (but clear on the radio), and the tall, tender and slightly bending young man as he said: ‘With this ring I thee wed, and with my body I thee worship.’

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So it was decades later that this particular change to tradition — the lack of “obey” — was first embraced at a major royal wedding: Princess Diana and Prince Charles, in their 1981 wedding, both promised simply to have, hold, love and cherish. (She did mess up her new husband’s name, though.)

Some royals continued to promise to obey even after that, but Prince William and Kate Middleton followed his parents’ footsteps.

And they weren’t alone. When the Cambridges wed in 2011, a member of the Church of England General Synod told the Telegraph that the vow of obedience was “relatively rare” in modern weddings.

So Markle’s decision on the “obey” question shouldn’t surprise anyone. Especially for a long-time advocate for women’s rights, the equality of vows is fitting — and as she has said that she plans to continue that advocacy as a member of the royal family, her adherence to modern royal tradition is fitting too.

Write to Lily Rothman at lily.rothman@time.com.