The heart has long been used as a symbol to refer to the spiritual, emotional, moral, and in the past also intellectual core of a human being. As the heart was once widely believed to be the seat of the human mind, the word heart continues to be used poetically to refer to the soul, and stylized depictions of hearts are extremely prevalent symbols representing love.

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As metaphor

In mythology, spirituality and religion

In religious texts the heart has historically been ascribed much mystical significance, either as metaphor or as an organ genuinely believed to have spiritual or divine attributes.

In Egyptian mythology, the Egyptian soul (heart) was weighed in a balance against the feather of Ma'at, symbolising truth, in the judgment of the dead in the Egyptian Book of the Dead. Egyptian sources do not actually reveal whether the heart had to be lighter or heavier than the feather for the deceased to pass into paradise - all depictions show only the weighing of the heart, not the actual results, heavier or lighter.

Similarly, in the Bible, this idea emerges in the earliest passages; Genesis 6:5 situates the thoughts of evil men in their hearts, and Exodus 5 through 12 speak repeatedly of the Lord "hardening Pharaoh's heart." By this it is meant that God made Pharaoh resolve not to let the Israelite slaves leave Egypt, in order to bring judgment against Pharaoh and demonstrate his power: "'Go to Pharaoh, for I have hardened his heart and the hearts of his officials so that I may perform these miraculous signs of mine among them'" (Exodus 10:1). In the Book of Jeremiah 17:9, it is written that the Lord is the judge who "tries" the human heart.

The Sacred Heart of Jesus and the Immaculate Heart of Mary are traditional Roman Catholic devotion]al images.

In early science and philosophy

Many classical antiquity philosophers and scientists, including Aristotle, considered the heart the seat of thought, reason or emotion, often rejecting the value of the brain.

The Stoics taught that the heart was the seat of the soul.

The Roman physician Galen located the seat of the passions in the liver, the seat of reason in the brain, and considered the heart to be the seat of the emotions. While Galen's identification of the heart with emotion were proposed as a part of his theory of the circulatory system, the heart has continued to be used as a symbolic source of human emotions even after the rejection of such beliefs.

These themes were reiterated in the European Middle Ages.

As icon

In European traditional art and folklore, the heart symbol is drawn in a stylized shape. This shape is typically colored red, suggesting both blood and, in many cultures, passion and strong emotion. The hearts have constituted, since the 15th century, one of the red suits in most playing card decks. The shape is particularly associated with romantic love; it is often seen on St. Valentine's Day greeting cards, candy boxes, and similar popular culture artifacts as a symbol of romantic love.

What the traditional "heart shape" actually depicts is a matter of some controversy. It only vaguely resembles the human heart. Some people claim that it actually depicts the heart of a cow, a more readily available sight to most people in past centuries than an actual human heart. However, while bovine hearts are more similar to the iconic heart shape, the resemblance is still slight.

The "heart" shape could also be considered to depict features of the human female body, such as the female's pubic mound or spread (vulva). The tantric symbol of the "Yoni" is another example of a heart-shaped abstraction of a woman's vulva. In the introduction to The Vagina Monologues Gloria Steinem writes, "[The heart] was reduced from power to romance by centuries of male dominance."

Another possible origin can be seen on the coins of the ancient city of Cyrene, some of which depict the seeds or fruit of the now-extinct silphium plant. The seeds are distinctly heart-shaped. Since this plant was widely used as an ancient herbal contraceptive or abortifacient, this shape may have come to be associated with sexuality and love.

The "heart" shape is formed by the back and wings of a dove, which was associated with Aphrodite, the ancient Greek goddess of love.

The most common emoticon for the heart is <3. There are several unicode heart symbols available:

"I Love..."

The heart symbol (♥) is used in slang expressions to indicate love or affection, sometimes with a connotation that the feeling is superficial or juvenile. It is a play upon Milton Glaser's classic I Love New York logo (typeset "I ♥ NY"). In the U.S., it can be used to show that one has a crush on someone or is in love with someone (i.e. "I ♥ [someone's name]" or "[Someone] ♥s [Someone else]").

The widespread use of this expression has inspired many parodies. Originally pronounced "I love", hipsters have taken to facetiously verbalizing it as "I heart", in expressions such as "I heart you!". Other examples include:

The equation (x^2+y^2-1)^3=x^2*y^3 yields a heart shaped graph.

See also