"You’ve gotta have heart, miles and miles and miles of heart." So crooned Eddie Fisher in his rendition of the hit tune "Heart" from the Adler and Ross musical comedy "Damn Yankees." The show premiered on Broadway in 1955 and I’m not sure the lyricists knew how right they were, in a sense, about those "miles and miles and miles."

In his recent book, "Heart: A History," Sandeep Jauhar explores just how essential that organ is to us, metaphorically as well as biologically. "Each heartbeat," Jauhar tells us, "generates enough force to circulate blood through approximately 100,000 miles of vessels." And in the average lifetime the human heart pulses 3 billion times, more or less.

The fetal heart begins to beat at around six weeks, about the same time as the first fetal brain activity. Even after an animal is medically "dead," the heart has been known to beat for days or even weeks. In a laboratory setting the heart tissue of chickens, nourished with water and blood plasma, has continued to pulsate for 20 years. Individual heart cells pulse on their own in a petri dish and are drawn to join and synchronize with other cells, becoming, as Jauhar puts it, "social entities."

Our hearts speed up or slow down in concert with our thoughts and emotions, as fear, anger, sexual excitement, or other passions arise and subside. It is no wonder then that the ancient Greeks and Romans viewed the heart and not the brain as the center of our mind and soul.

The ancient Greek word for heart was cardia; the Romans called the organ cor/cordis. The words' stems card- and cord- and our word "heart" are what linguists term "cognates," from a Latin word meaning "born together," because they share a common linguistic parentage. Though they may not look quite alike, say all three aloud and you can hear and feel their likeness: cord/card/heart. The h- of "heart" has a bit of the throaty hard c- tone (compare the cognates "horn" and "cornet/cornucopia"), and the final –t and –d are "dental consonants," so-called because we move our tongue to the back of our upper teeth to produce both sounds, which are essentially identical except that we vibrate our vocal chords for the –d (b and p share a similar connection, both formed by pursing our lips, the b "vocalized," the p not).

The reason for the similarity is simple. All three words derive from a common ancestral language known as Proto-Indo-European that dates back 5,000 years and more, long before written records, and was spoken by a society originally located in Eurasia in the area of modern Ukraine and Russia. Like us and all humans, these prehistoric folk felt their heart throbbing, knew it was vital, and called it something like ker(d). As the Indo-Europeans migrated southward for warmer climes, the sound, and eventually spelling, of the word evolved differently in the different regions in which they settled, including the territory of the Anglo-Saxons (where in Old English the word was heorte), the Romans, the Greeks, and in India where the word in their ancient language of Sanskrit was hrd or hrdyam (again, like Greek cardia).

CARDiology, "study of the heart," comes to us from Greek, and Greek and Roman physicians knew something of the heart’s functioning, that it had valves and pumped (or sucked) blood through the veins and arteries. Aristotle thought it created blood. It was widely believed that the organ was at the CORe, the life-center, of the body, and that it was the seat not only of the emotions, but of the mind and intellect.

Many other English derivatives reflect ancient views of the heart’s role in our behavior. We are indebted to Greek more for such medical terms as CARDiac, electroCARDiogram (ECG), and myoCARDial. But from Latin come a host of words related to emotional matters and affairs of the heart: a CORDiality is sincere, heartfelt affection; a COURageous woman has a brave heart; to enCOURage someone is to help him take heart; you reCORD memories you want to keep in your heart; if your heart and a friend’s are aligned, you are in acCORD, and if not, your relationship may be fraught with disCORD.

And speaking of relationships, here’s some heart-to-heart advice for this Valentine’s Day, which of course was named for ancient Rome’s Saint Valentinus (or for ONE of the three). Send your sweetheart a card inscribed with some heartfelt blandishments; one character in Roman comedy tried calling his girl cor meum, spes mea, mel meum, "my heart, my hope, my honey." If that kind of sweet-talking doesn’t work, try giving her a heart-shaped box of cherry CORDials. She’s sure to see you’ve got miles and miles of heart.

Rick LaFleur is retired from 40 years of teaching Latin language and literature at the University of Georgia, which during his tenure came to have the largest Latin enrollment of all of the nation’s colleges and universities; his latest book is "Ubi Fera Sunt," a lively, lovingly wrought translation into classical Latin of Maurice Sendak’s classic, "Where the Wild Things Are," ranked first on TIME magazine’s 2015 list of the top 100 children’s books of all time.