Placebo: the Latin word that means «I shall please»

When a clinical trial gives a group of patients a pill with no active ingredient, that pill is called a placebo. The word sounds like modern medical jargon, but it is actually pure Latin and was not born in a laboratory: it means «I shall please», «I will be pleasing», and before it reached the pharmacy it passed through a medieval funeral chant and an accusation of flattery. The story of how a courteous promise ended up naming a fake pill is one of those routes only language can travel.

A promise in the future tense

«Placebo» is the first-person future of the Latin verb placere, «to please» —the same root behind «pleasure», «placid» and «complacent»—. Literally it means «I shall please», «I will be agreeable». It was not a rare or technical word: any Latin speaker would have understood it as a promise to please someone.

The leap into religious vocabulary came in the early thirteenth century. In the Catholic Office of the Dead, the Vespers for the dead opened with an antiphon taken from Psalm 116 in the Latin Vulgate: «Placebo Domino in regione vivorum», «I will please the Lord in the land of the living». Because that chant began with the word placebo, the ceremony itself came to be known popularly as «singing placebo».

From the funeral to the flatterer

Here the word took an unexpected and unflattering turn. In the Middle Ages it was common for people who were not relatives of the deceased to attend funerals —sometimes hoping for a meal or alms— and to join enthusiastically in «singing placebo». So «to sing placebo» came to mean, contemptuously, to fawn: to flatter someone in a servile, self-interested way.

The sense stuck so firmly that in the fourteenth century Geoffrey Chaucer, in the Canterbury Tales, named a flattering character outright «Placebo», a man who always agrees with his rich brother. For a couple of centuries, calling someone «a placebo» was accusing them of being a fawning courtier. Medicine still had nothing to do with it.

When it entered medicine

The medical use is surprisingly late. Toward the end of the eighteenth century, English medical dictionaries began to record «placebo» with a new meaning: a remedy prescribed «more to please than to benefit» the patient. Motherby's New Medical Dictionary of 1785 already lists it, and by the early nineteenth century the definition of «a medicine given to please» was fixed. The link with the old meaning was transparent: the doctor gave something pleasing and reassuring, even if it cured nothing.

It is the same kind of linguistic fossil we find in other everyday medical words, as when we discover that «vaccine» hides a cow or that «nostalgia» was a real medical diagnosis. Language keeps whole stories inside terms we use without thinking.

The first scientific proof

That giving something «to please» could genuinely relieve a patient stopped being an intuition and became an experiment thanks to the English physician John Haygarth. In the late eighteenth century the «Perkins tractors» were fashionable: metal rods patented in 1796 by the American Elisha Perkins that supposedly drew disease out of the body when passed over the skin. They sold at high prices and had devoted admirers.

Haygarth was skeptical. In 1799 he made fake rods of painted wood, identical on the outside but lacking any of the supposed electrical properties, and treated rheumatism patients with them without revealing the trick. The result was revealing: four out of five patients said they felt better with the fake tractors, just as with the real ones. He published his findings in 1800 in a book whose title summed it all up: Of the Imagination, as a Cause and as a Cure of Disorders of the Body. Without yet using the word, Haygarth had demonstrated the placebo effect.

The placebo reaches the modern laboratory

The concept took a while to become scientific rigor. The decisive step came in 1955 from the Harvard anesthesiologist Henry K. Beecher with a famous paper, The Powerful Placebo, in which he argued that, on average, a third of patients improved with placebo alone. His influence was enormous: it helped cement the idea that a new treatment must be compared against a placebo in double-blind trials —where neither patient nor doctor knows who receives what— before being accepted. It is the standard by which medicines are approved today.

Honesty is in order: later analyses have heavily qualified Beecher's figures, and we now know that much of what he attributed to placebo was in fact the natural improvement of illness over time. The placebo effect exists and is real, especially with pain and other subjective symptoms, but it is more modest and complex than popular legend suggests. Modern medicine —the kind that made possible things like the anesthesia that ended the pain of surgery— was built precisely by learning to separate the real effect from the wish to please.

So the next time you hear «placebo», remember that you are pronouncing an old Latin promise —«I shall please»— that began by being sung beside a coffin, became an insult for flatterers, and ended up naming one of the most fascinating phenomena of mind and body.

References

1. Douglas Harper, Online Etymology Dictionary, s. v. «placebo». etymonline.com
2. «Origin of 'Placebo' and 'Placebo Effect'», Merriam-Webster. merriam-webster.com
3. «Haygarth J (1800)», The James Lind Library. jameslindlibrary.org
4. Henry K. Beecher, «The Powerful Placebo», JAMA (1955). en.wikipedia.org

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