Look into a Torah scroll or Tehillim and you’ll discover that very often G‑d’s name is written as four Hebrew letters: yud, hei, vav, hei. However, this name is never actually said aloud by Jewish people, and it is unknown how to pronounce it. Instead, it’s usually read as A-do-nai, another sacred name of G‑d that roughly translates as “my Master.”

When referring to this unpronounced name, we sometimes use the terms Shem Hamiyuchad (“Unique Name1”), Shem Hameforesh2 (“Explicit Name” or “Separated Name,” since it is separate from all other names) and Havayah (lit., “Being,” as it expresses His transcendence of time and space).

In English, this ineffable name is sometimes referred to by the Greek name Tetragrammaton.

Now, why is it unknown? Can’t one simply read it off the page of a Chumash or Tehillim?

The key here is that, contrary to popular belief, the vowels that appear with these four letters in many printed texts are not an indication of how they are to be pronounced. Rather, they indicate which of G‑d's other names are to be substituted in the verse. When it is pronounced like A-do-nai, it is given the vowels of that name, and when it is pronounced like E-lo-him, it is given those vowels. But the actual pronunciation of the name of G‑d is unknown.

So what’s the point of a name that’s never pronounced? And was there ever a time in history when it was pronounced?

“Not As I Am Written Am I Pronounced”

When speaking to Moses at the Burning Bush, G‑d said: “This is My name forever, and this is how I should be mentioned in every generation.”3

As the sages of the Talmud explain, this verse tells us that G‑d has an eternal name, which is separate from how it’s actually pronounced by Jews of all generations.4

But there was a major exception. In the Holy Temple, the priests would confer the Priestly Blessing every day, pronouncing the name as it was written.5 The High Priest uttered this name a total of 10 times throughout the Yom Kippur service.6

Maimonides7 explains that they taught not just the pronunciation—which vowels were to be applied and which letters were to be stressed—but also the metaphysical secrets it contained.

As the mystics explain, this ineffable name of G‑d is the only “true” name. It represents the essence of His reality, from which all creation flows. From this perspective, nothing besides Him truly exists. The other Divine names veil the true Divine essence of reality and are the interfaces through which He brings into being and interacts with creation.

Reflecting this, we substitute His name with the lesser names of A-do-nai and E-lo-him, which represent the dynamic of Him interacting with creation.

Historically, great, righteous individuals, to whom the Divine Presence was revealed, were able to articulate the essence of the Divine name because they saw themselves and the world around them as being nothing before Him.

Hiding His Ineffable Name

Although the priests in the Temple originally used G‑d’s ineffable name, the spiritual state of the Jewish people declined over the generations. There came a time, following the passing of the High Priest Simeon the Righteous, when the priests ceased uttering G‑d’s name in the Priestly Blessing in the Temple, lest it be learned by people lacking proper stature and moral conduct.8

At that point, many of the miracles that took place daily in the Holy Temple ceased to appear regularly. Some say that this was the reason G‑d’s name was no longer pronounced, for if the Temple was not a place where His presence was as readily apparent, then this name was not to be said.9

From this point on, once every seven years, the Sages would only teach the secret of pronouncing the name to their students and sons who had proven their moral conduct.10

12-Letter Divine Name

So what name was used instead? Maimonides further explains that the sages would employ a 12-letter name of G‑d (as well as a 42-letter name),11 which was considered less holy than the Tetragrammaton but more special than the name A-do-nai, which we use today. Now, this name was not a single word but comprised a number of words with a total of 12 letters.

The sages would use this name whenever they encountered the 4-letter name in Scripture. It was freely taught to anyone who wished to learn it, and it was used by priests conferring the Priestly Blessing in the Holy Temple.

However, as the generations regressed, the time came when this 12-letter name needed to be made secret as well. From then on, it was only entrusted to the most worthy priests to use during Priestly Blessings in the Temple, who would say it in a low voice so that it be drowned out amid the singing of their peers.12

The Mishnah states that a person who pronounces the 4-letter name is undeserving of a share in the World to Come.13 And indeed, the great sage Rabbi Chanina ben Teradyon died a martyr’s death as Divine punishment for pronouncing the ineffable name of G‑d in public.14

Power Over Life and Death

When someone utters the name of G‑d, it triggers a particular spiritual illumination that affects the physical realm. A classic example is Moses killing the Egyptian slave driver by using G‑d's ineffable name.15

According to some authorities, this power is accessible only to those deeply connected to G‑d.16 Others explain that by uttering the name, even an ordinary person with no understanding of its inner meaning can override nature to some extent.17

The Midrash relates that when G‑d gave the Torah, He also gave each Jew two “crowns” engraved with the ineffable name, through which they would have dominion over the Angel of Death. But due to their sins, these crowns were taken away from them, and will be returned in the messianic era18—may it be speedily in our days!