The Mysterious Origins of the Enduring Heart Symbol

As for how to represent that impassioned organ, the lack of real knowledge of physiology left open fanciful possibilities. The second-century Greek physician Galen asserted that the heart was shaped like a pinecone and worked with the liver. This view carried into the Middle Ages, when the heart first found its visual form as the symbol of love.

The earliest illustrations of the amorous heart, created around 1250 in a French allegory called “The Romance of the Pear,” pictured a heart that looks like a pinecone, eggplant or pear, with its narrow end pointed upward and its wider, lower part held in a human hand.

In one miniature, a kneeling youth offers such a heart to a standing lady, who raises her hand in a gesture of surprise. In another, a lady dressed in pink extends a similar heart to a young man. Medieval viewers would have interpreted these scenes as “heart offerings,” a theme already popular in sentimental stories and songs.

Other artists and artisans quickly picked up the iconography. One of the most famous examples, now in the Victoria and Albert Museum in London, was carved in ivory around 1300 on the back of a French mirror. A man kneels before his lady and offers her his upside-down, pointed heart while she raises a large hoop above his head. Medieval artisans, without the benefit of Freud, knew exactly what they were doing when they used such sexually suggestive symbols.

But this same pinecone-shaped heart also found its way into religious works of art. When Giotto, in 1305, painted the theological virtue of “Caritas” (usually translated as “charity” or “love”) among the panels that adorn the Scrovegni Chapel in Padua, he pictured a capacious woman lifting her heart toward a haloed, bearded figure, presumably Christ or God. Giotto’s “Caritas” influenced subsequent Italian painters and sculptors, whose works still grace the churches and museums of northern Italy.

Whether intended for a loved one in secular manuscripts or for God in Christian art, these symbols expressed the meaning of the heart as love, but they still did not share the form that we know today. That shape evolved during the first decades of the 14th century, starting with images in the work of another Italian, Francesco da Barberino.

In his book called “Precepts on Love” (“Documenti d’Amore”), we see for the first time symmetrical hearts with rudimentary lobes strung across the neck of a horse (though, truth be told, they also look a good deal like triangles). Standing atop the horse is the figure of Cupid bearing arrows in one hand and a branch of roses in the other. Cupid races off victorious with the hearts he has pierced, leaving behind a row of love-struck individuals.

We finally find a clear instance of our contemporary heart icon in a French manuscript titled “The Romance of Alexander,” circa 1340. In the bottom border of one page, on the left-hand side, a woman raises a symmetrical heart with two clearly defined lobes that she has received from the man facing her. She accepts the gift of his heart, while he touches his breast to indicate the place from which it has come. Another couple in the same border, on the right-hand side, shows a very different scene: A lady turns away from a suitor who offers her a purse.

The two couples present a graphic vision of how men and women should and should not relate to each other. One is pure and inspired by feelings from the heart, the other is venal and based on material rewards.

From then on, the stylized heart became ubiquitous, not only on the pages of manuscripts but also on luxury items like brooches, pendants, rings and tapestries. Though a few medical pioneers began to observe directly the true ungainly shape of the human heart—so different from the popular symbol—artists and artisans remained faithful to the symmetrical, scalloped form.

The great exception, in this as in other matters of art and science, was Leonardo da Vinci, who studied both human and animal dissections. The painstaking illustrations in his notebooks show his longstanding dedication to anatomical accuracy. (Human dissection, long taboo, began appearing as early as 1315 in Italy, but it could be banned at any time, according to the mood of the pope.)

Andreas Vesalius, the 16th-century Flemish physician who is considered the father of modern anatomy, was allowed to dissect cadavers at the University of Padua, thanks to a judge who supplied him with the bodies of executed criminals. In his groundbreaking book “The Fabric of the Human Body” (“De humani corporis fabrica”), Vesalius corrected certain errors made by Galen that had been blindly repeated by successive generations of doctors since the second century.

The detailed plates in Vesalius’s “Fabrica,” like the drawings in da Vinci’s notebooks, pictured a heart that looked more like the real thing. Yet the advance of science did nothing to shake popular attachment to the image of the heart as bi-lobed at the top and pointed at the bottom.

What explains the symbol’s appeal and durability? Perhaps it is because the shape, with its two halves forming a single figure, so perfectly captures the Platonic idea of love as the longing to merge with an ideal soul mate. More unconsciously, and on a less ethereal level, perhaps its success has to do with its subtle evocation of the breasts and buttocks of the human body.

Over the centuries, the heart emblem has taken on new meanings and functions. It survived the Reformation, which set aside so much other traditional Catholic iconography, largely because Martin Luther constructed his personal seal from a red heart placed within a white rose, with a black cross at the center. Having thus been preserved for Protestants, it was available in the 19th century for romance-minded English and American consumers, who began to trade mass-produced valentines featuring hearts. In 1977, the heart icon even became a verb, with Milton Glaser’s famous and endlessly repurposed “I [heart] NY” logo.

Today, the stylized heart symbolizing love reigns supreme throughout the world. It may be only a metaphor, but it serves us well as a universal sign for the mystery of love.

—Dr. Yalom is a senior scholar at the Clayman Institute for Gender Research at Stanford University. This essay is adapted from her new book, “The Amorous Heart: An Unconventional History of Love” (Basic Books).