What makes the perfect passionate kiss? 5 tips from history

You’ve booked the restaurant, chosen the outfit, and selected a romantic spot for the perfect nightcap. But have you planned the kiss?

I’m a historian and author of The Kiss: A History of Passion and Power. As the annual festival of love descends, European history has some tips for those getting ready to pucker their lips.

Open mouth to exchange breath

Medieval Christians valued the kiss as a symbol of unification, smooching each other on the mouth during worship. They believed the kiss allowed for a sharing of souls, and therefore needed to explain how that happened.

The open mouth allowed an exchange of breath, and with that, of spirits. As the English Cistercian monk Aelred of Rievaulx (1110–47 CE) explained:

from this mingling of spirits, there grows up a kind of mental agreeableness, which elicits and joins together the affection of those who kiss.

Love was the product of a shared breath.

The idea that the open mouth kiss enabled a union of souls remained popular well into the 20th century.

A kiss of homage, marginalia in a 13th century manuscript copy of the laws of the 9th century king Hywel Dda, National Library of Wales, Peniarth MS28. National Library of Wales

Kiss deeply

Medieval and early modern European ideas about the kiss drew heavily on the bible book Song of Songs, love poetry that they interpreted as an allegory for the relationship between God and humankind. Drawing on this inspiration, kisses were always expected to be fulsome.

Here’s how Robert of Deutz, a 12th century French Benedictine theologian, spoke of his vision of a passionate encounter with Jesus Christ:

I took hold of him whom my soul loves, I held him, I embraced him, I kissed him lingeringly. I sense how gratefully he accepted this gesture of love, when between kissing he himself opened his mouth, in order that I kiss more deeply.

Ecstatic encounters with the divine continued over the centuries. Five hundred years later, the Presbyterian minister Samuel Rutherford expressed his relief when, after a period of religious doubt, he entered into God’s presence:

he hath taken the mask of His face, and saith ‘Kiss thy fill’.

A passionate holy kiss was not a quick peck. Instead human-divine lovers lingered, kissed deeply, and took their fill.

Wear lipstick

With the growth of dating culture in the early decades of the 20th century, fashionable young women wanted to kiss without misadventure. Cosmetic companies rose to the challenge, offering “kissproof” lipstick that allowed smooching without streaks.

In 1936, actor Gary Cooper was asked, in an advertising campaign, to select from three women: one wore no lipstick, one had ordinary lipstick, and a third used Tangee, a popular brand. Cooper selected Tangee because “her lips look kissable … they glow with natural colour”.

For many young people, lipstick became part of the experience of the kiss. The male protagonist in Graham Greene’s 1938 novel Brighton Rock was disappointed with his bride’s natural mouth:

He would have preferred the taste of Coty powder or Kissproof lipstick or any chemical compound.

Lipstick provided a smell and taste that became associated with a desirable kiss.

Pulse racing

In 1963, Miami University administrators were alarmed to discover that students had created a “kiss-o-meter” – a device they felt contravened public decency.

This machine measured the electric current that surged through the body as a couple kissed, and displayed the output on a scale from “dead fish” to “wowee”.

Kiss-o-meters had been used by scientists since the early 20th century, as one of several devices that sought to translate electric current, blood pressure, or heart rate into insight about a person’s emotions. In theory, the higher the response, the greater the feeling.

By the 1960s, such technology had little scientific legitimacy, but similar principles shaped 21st century technologies, such as the MEG machine that imaged blood flow in the brain.

In 2009, Sheril Kirshenbaum, a scientist at Michigan State University, worked with neuroscientists at the Poeppel Lab to measure the pleasure of the kiss by displaying pictures of people kissing to participants sitting in an MEG machine.

The scientists thought the ideal kiss would be one that stimulated the body – causing blood to flow, nerves to pulse and hearts to beat. Unfortunately, the results of their experiments were ambivalent and hard to repeat. If an ideal kiss should be stimulating, in practice, many weren’t!

On a less scientific note, the kiss-o-meter also became a popular arcade game.

Ask for consent

At many points in European history, stealing a kiss was treated rather lightly – the subject of humour. However, underpinning these jokes was often a concern about power.

In 17th century England, taking a kiss from a woman without permission from her father or husband was interpreted as an insult to the man ignored.

In the 19th and early 20th century, women’s rights activists showed concern about the indiscriminate kisses applied to young women.

As American feminist Clara Belle complained in 1909:

It would take a quick and ever-alert dodger to escape all the kisses that are aimed at girl’s face.

Following the #metoo movement, a new script for the kiss emerged. The 2025 contribution to the Bridget Jones film franchise shows a young male lead asking permission to kiss Bridget. “Oh, a generation who asks”, Bridget thinks. A passionate kiss, preceded by permission.