What is the golem of Prague, and where does the legend come from?

In Jewish folklore, a golem is a human-shaped figure made from lifeless material, usually clay or mud, and brought to life through holy words. The most famous golem belongs to Prague. According to the legend, Rabbi Judah Loew ben Bezalel, a great scholar of the late 16th century, shaped a man from clay, animated it with a divine name, and used it to serve and protect the city's Jewish community.

The story has become one of the most quoted images in discussions about technology: a powerful helper that does exactly what it is told, sometimes with results its maker did not intend.

Where the word comes from

The word golem is very old. It appears once in the Hebrew Bible, in Psalm 139:16, where it refers to an embryo, something not yet fully formed. Later Jewish tradition used it for anything unfinished. One ancient rabbinic text describes the first hours of Adam's creation and says that, at one stage, he was a golem: a shapeless mass waiting to be given form and life.

The Talmud, the great collection of rabbinic discussion, includes a short and striking story. A rabbi named Rava creates a man and sends him to another rabbi, Rav Zeira. Rav Zeira speaks to the man, but the man cannot answer, so Rav Zeira tells him to return to dust. The made man can move, but he cannot speak. Hold on to that detail; it will come back.

How a golem is brought to life

In the Middle Ages, a belief grew that life could be given to a clay or wooden figure using the Sefer Yetzirah, the "Book of Creation," an early mystical text about the letters of the Hebrew alphabet. The earliest known written instructions for making a golem come from Eleazar of Worms, in the late 12th or early 13th century.

The method, as the legends tell it, works like this:

Step	What happens in the legend
1. Shape	A human figure is formed from clay or earth.
2. Combine letters	Letters of the Hebrew alphabet are combined to form a shem, one of the names of God.
3. Place the name	The shem is written on paper and put in the golem's mouth or on its forehead.
4. Activate	The figure comes to life and obeys its maker's orders.
5. Deactivate	Removing the name returns the golem to lifeless clay.

Some versions add a clever twist. The Hebrew word emet, meaning "truth," is written on the golem's forehead. Erase its first letter and what remains is met, meaning "dead," and the golem stops.

The Prague story

The best-known telling goes like this. Rabbi Loew made a golem and used it as a servant during the week. Every Friday afternoon he removed the name from its mouth so that it would rest on the Sabbath, the weekly day of rest. One Friday he forgot. Afraid the golem would break the Sabbath, he ran after it, stopped it outside the synagogue moments before the day of rest began, and pulled out the name. The golem fell to pieces. Its remains, the story says, lie in the attic of the Old New Synagogue in Prague.

Later versions add that Rabbi Loew made the golem to defend the community from attacks during the reign of Emperor Rudolf II, and some describe it growing violent and out of control.

Before Prague, a similar story was told about Rabbi Elijah of Chelm in the mid-16th century, the first person credited with making a golem by means of a divine name. His golem, the tradition says, kept growing until he feared it would destroy the world, and he removed the name.

How old is the Prague legend?

This is where precision matters. Rabbi Loew was a real and important rabbi in late 16th-century Prague. But historians generally agree that the story linking him to a golem appeared much later. The first written versions date from the 1830s and 1840s, in German, by Jewish writers. No Hebrew book from the 16th, 17th or 18th centuries, even those printed in Prague, says that he made a golem, and he does not mention one in his own writings.

A 1909 book presented as an eyewitness account by Rabbi Loew's son-in-law did much to spread the story, but scholars widely regard it as a literary hoax. So the golem of Prague is best described as a 16th-century setting for a legend shaped mostly in the 19th century, built on ideas that go back more than a thousand years.

Try it: Write a one-line instruction you might give a helper, such as "Fill the water jug." Then list every way someone following it with perfect literalness could get it wrong (overflowing, refilling forever, filling the wrong jug). This is the golem problem in miniature.

Why do people compare AI to the golem?

Because the golem captures several worries that are very much alive in 2019.

The first is literal obedience. In many tellings the golem is not intelligent; it carries out orders exactly as given. One story describes a golem that, because of a small mistake in its instructions, started a fire that burned down a town. Anyone who has written software knows that feeling: computers do what you say, not what you mean.

The second is control. The golem is useful as long as its maker can switch it off, and dangerous the moment he forgets. Today's debates about AI often turn on the same question: how do we make sure a powerful system can be stopped or corrected? Just last month, OpenAI chose not to release the full version of its GPT-2 language model, citing concerns about misuse, a decision that has sparked lively debate about how much control creators should keep over what they build.

The third is language. The Talmud's made man could move but not speak, and speech has long been treated as a sign of a real mind. That same test runs through the history of AI, from early chatbots to the text generators in this year's news. The golem story reminds us that a figure can be busy and useful without understanding a word.