At the birth of a Muslim child, verses of the Koran are recited into the ear of the newborn, signifying a blessing and a hope that the holy book will resonate strongly in that child's life.
From then on, the words of the Muslim scripture structure and shape that life. The child learns Arabic in order to read the Koran in the original language, perform the five daily prayers, repeat key phrases before all significant acts and events, and make it the guide for daily living.
"In a way, the soul of the traditional Muslim is like a mosaic made up of phrases of the Quran," writes renowned scholar Seyyed Hossein Nasr in "The Heart of Islam."
For one-fifth of the world's population, those scriptures are the literal word of God, revealed to the prophet Muhammad by the angel Gabriel (Koran means "recitation").
"It is as close as you can get to the transcendent.... To use one analogy, the Koran is to Islam what Jesus is to Christianity," explains John Esposito, university professor at Georgetown University in Washington, D.C., in an interview.
That begins to explain the intensity of street protests last week in several Muslim countries after reports (later retracted) that US military interrogators had desecrated the Koran. It was a reaction that, to American sensibilities, may seem puzzling.
But Dr. Esposito says that is due partly to Western secularization and a lost sensitivity to degrees of sacredness.
"While we've become a more religious nation in one sense, we have also become, in our sense of the sacred, less sensitive and aware," says the author of "What Everyone Needs to Know About Islam."
The sacredness of the Koran to Muslims is expressed even in their relationship to its physical presence, Esposito says. "Pious Muslims will always put the Koran on top of everything else, in a special place; you don't put it under books or on the floor."
It's a relationship many in the US may find surprising. "We don't understand why someone would go through the roof about desecrating a sacred book, but we do understand why they would do so about desecrating or burning a flag," says Esposito.
Yet he says the street riots occurred because of the political context, too - the presence of US troops in Afghanistan and Iraq, accusations of abuse at Abu Ghraib, and other allegations about the detainee prison at Guantánamo.
While most Muslims don't take to the streets, they are pained by the disdain for Islam any desecration would entail.
"The potency of the Koran for Muslims worldwide can't be denied," says Arsalan Iftikhar, legal counsel for the Council on American-Islamic Relations (CAIR.) Part of the problem, he says, is that Muslims sense that many Americans still haven't distinguished between extremism and mainstream Islam, and that they fail to recognize it as one of the world's great religions, treasured by millions.
"My love for the Koran began at a very early age - I began to learn Arabic when I was 4 years old in order to read it," he says. "That has helped me have a much more intimate relationship with God, to read what I believe to be God's holy book in the language it was revealed in."
The Koran deals with the nature of reality and the cosmos, moral and spiritual lessons, laws for the individual and society.
Both "its inner meaning, or spirit, and its body ... the text in the Arabic language ... are sacred," Dr. Nasr wrote.
No matter where a Muslim lives, prayers are said in Arabic, and translations of the Koran are seen as "interpretations," with Arabic found on the facing page. This has given rise to the art forms of calligraphy and recitation of the Koran.
Many Muslims memorize the entire book - not quite the length of the New Testament - which is considered a noteworthy achievement. Children vie actively in recitation competitions.
"There's a specific Islamic science called tajwid, which focuses on recitation in a very melodic sense, and I competed in tajwid competitions," says Mr. Iftikhar, who grew up in Chicago. "There are favorite imams around the world, and some have a 'rock star' following. People will buy recitations because they like the sound of his voice."
They also flock to stadiums for performances the way Americans do to sports events or concerts.
"The greatest miracle of Islam is said to be the eloquence of the Quran," Nasr writes. Its beauty has moved Muslims and non-Muslims through the ages and brought converts into the faith.
Aminah McCloud, professor of Islamic studies at DePaul University in Chicago, first picked up the Koran as a teenager and read it daily for five months. "I found it an awesome text, something that not only had stories but challenged you to think," she says.
Not considered a new revelation, but the one truth God has revealed through prophets such as Abraham, Moses, and Jesus, the Koran includes stories of biblical figures. But Muslims see Muhammad as the final prophet, and the Koran as "the straight path" to fulfilling God's purpose.
Over the 23-year period in which Muhammad received the teachings, his companions memorized them and scribes wrote them down, scholars say; the complete text was put together some 20 years after his death in AD 632.
The 114 chapters are not arranged chronologically or thematically, but run from the longest to the shortest.
"Like the Bible and Torah, the Koran has many stories ... meant to serve as examples for how people should go about their lives," says Iftikhar. "For example, if I have great trials in my life, I think of the story of Job - his faith never wavered."
In response to the desecration controversy, CAIR this week announced it would give a Koran to any interested American (www.cair-net.org).
"Any holy book is a wealth of knowledge; regardless of how often you've read it, you can learn something new each time," Iftikhar says. "That's the marvel - always there is a resource, a comfort, a reaffirmation."