To know the Holocaust in great detail is one thing. But to hear and feel it from the souls of those who were in the midst of it becomes a singular revelation in the monumental new book Our Will to Live by the Philadelphia-born violist Mark Ludwig. Besides playing in the Boston Symphony Orchestra for 36 years, he has spent the last three decades researching, promoting, and performing music written by the Jewish composers incarcerated at the Terezín concentration camp during World War II, from roughly 1941 to 1944.

Even for those who find Holocaust literature too painful to bear, this collection of artifacts by Jewish artists and musicians — subtitled The Terezín Music Critiques of Viktor Ullmann, Illustrations by Terezín Artists — is exhilarating in humanity-affirming ways. The 328-page hardcover book published by Steidl ($45) is superbly organized with sketches of the camp’s inner recesses, music programs, and a meticulously curated playlist that includes historic recordings made in the camp as well as modern recordings by Yo-Yo Ma. This isn’t just a book. It’s a world, and one that elicits almost every possible emotion.

Many of the artifacts here have been known for decades. But perhaps the world didn’t have the kind of historic perspective to truly understand and enter into them. Composers Ullmann, Hans Krasa, Pavel Haas, Erwin Schulhoff, and Gideon Klein have had international attention over the last few decades, thanks to Ludwig (also a member of the Hawthorne String Quartet), conductor John Mauceri, and recording producer Michael Haas, who masterminded the London/Decca-label series of recordings titled “Entartete Musik” (forbidden music under the Third Reich).

We know already that the Terezín composers are part of a lost generation that felt the polar opposite attractions of the rustic Leos Janacek and the cerebral Arnold Schoenberg. Meanwhile, the discovery of Nazi-banned pieces that were left behind when the Jewish composers who successfully fled the Third Reich has broadened the awareness of European music between the wars.

And never more than recently in a case of reverse circumstances: Berlin-based composer Eugen Engel got his opera manuscript Grete Minde out of Germany, though he was left behind and died in a concentration camp in 1943. Recently discovered in a San Francisco basement, the opera was premiered in Magdeburg on Feb. 13, with radio broadcasts revealing the opera as a lush cross section of the 1930s Korngold/Strauss sensibility.

The focus of the book, though, is Terezín, which was not a death camp like Auschwitz, though there were many deaths among the 142,000 Jews who passed through this remote Bohemian fortress town (aka Theresienstadt), en route to Auschwitz. The fact that 23,000 survived — some living long enough to be interviewed by Ludwig — is partly due to the camp’s use for Nazi propaganda purposes. International Red Cross inspections were periodic. A documentary film that tried to tell the world that Jews were not exterminated, and possibly had adequate treatment, included a glimpse of the children’s opera Brundibár, performed in the camp (and heard in the book’s playlist). But photos of those children don’t lie: However spirited their performance, sorrow is embedded in their faces.

“They [the Red Cross] appeared to be completely taken in by the false front put up for their benefit,” wrote Rabbi Leo Baeck in Terezín. “The effect on our morale was devastating. We felt forgotten and forsaken.”

On most days, Terezín was brutally overcrowded. Suicide was rampant. So were malnutrition and death. “Soups were made from powder. Nobody knows what was in the powder,” according to Edgar Krasa, who supervised kitchens. “Now it developed and it’s not nice but true — that it was not what you know, it was who you knew in Terezín. If you know the guy in the kitchen who was ladling out the soup, he went a little deeper and got you some potatoes in your soup.”

The lethargy of that existence is unimaginable until you hear Ullmann’s satirical opera, written in Terezín, The Emperor of Atlantis (which has been performed by the Curtis Institute). Early on, one character sings, “Each day just leaks into the other. ... One day, two days, who’ll buy new days? Lovely fresh days, undiscovered. ...”

Then, the opera’s title character (Hitler, obviously) is abandoned by his best friend, Death. “Who after this will still obey me?” exclaims the Emperor. “Does Death refuse his duty?”

Jews were no longer allowed to own musical instruments, but all manner of them made their way into the camp and into the hands of musicians who had been forcibly taken from Prague’s robust artistic community. The fact that any creativity happened is beyond remarkable.

Composer Haas — the star pupil of the great Janacek — arrived in Terezín in 1941, having divorced his non-Jewish wife to save her and their daughter from following him to Terez��n. He was in no mood to join the other incarcerated composers. Ludwig relates in one of his many illuminating footnotes: “In an attempt to engage and encourage Haas, the young Gideon Klein shared sheets of paper on which he had drawn musical staves.”

What drove this activity in Terezín under near-impossible conditions is summed up by Ullmann: “Our desire for culture was equal to our will to live.”

Initially, music was performed in secret, in the attics of the barracks. Ultimately, culture was sanctioned. Operas by Mozart were performed with whatever the approximate resources were at hand. Verdi’s mighty Requiem was performed by a chorus of prisoners with mere piano accompaniment, allowing the captive to stare the captors in the face while singing, “Dies Irae.” According to Edgar Krasa, “Even SS officers came from Berlin and Prague. Schachter [the conductor] wanted to make a musical protest to the Nazis sitting in the audience when we sang ... ‘the day of wrath and judgement’ ... but the Germans felt we were all singing our Requiem.”

Though nobody inside Terezín was sure what they were facing when sent to Auschwitz, the Nazis knew. “From time to time, one thousand unhappy souls would come here and another thousand unhappy souls would go away,” wrote 15-year-old Petr Fischl in his diary.

Many of the Terezín musicians had the foresight that they might never be seen again, and they left their manuscripts and papers behind, whether hidden in the floorboards of their barracks, or in trusted hands of fellow prisoners. Some 500 documents were saved by Karel Herman, who enjoyed a somewhat privileged position in the camp before he was shipped off to “the east” (Auschwitz) in 1944.

The various artifacts bring one’s awareness to an entirely new level. Sketches give detailed glimpses of what the stages looked like. Handmade programs for concerts capture the script and overall style of the prewar 1940s, with a dash of gallows humor for the 1944 “Ghetto Swingers” jazz concert.

But death looms in the book. Having listened to the extroverted jaunty music of Erwin Schulhoff, I was stunned to turn a page in Ludwig’s book to see a sketch of the composer on his deathbed — eyes closed, jaw slack. Another, Sigmund Schul, died at age 28 after a long illness. “We have lost a truly inspiring artistic personality,” wrote Ullmann. “It is no eulogy cliché if I say that he was absolutely justified when he uttered, shortly before his death, ‘What a pity that this is what has come of me.’ It was the truth.” Most of the other composers were murdered in Auschwitz.

The heart of the book is Ullmann’s music criticism. This is writing of the highest order — with sharp observations that go far to conjure up what he heard and felt. Example: The wine-women-and-song waltzes of Johann Strauss’ Die Fledermaus fell flat for him. “Dancing on the tombs of the future and at our expense” was how he described the experience. “We take a sip of its champagne,” he wrote, “but we remain sober.”

Music written in Terezín wasn’t likely to be easygoing stuff, and it isn’t: These were major compositional personalities in a confrontational era with music being reinvented in all sorts of ways — with J.S. Bach hovering in the background. Ullmann’s String Quartet No. 3 is a particularly rigorous, compact, durable work. The brightest light was the multitalented Klein. Comparisons to Leonard Bernstein aren’t facile: The two were about the same age and even looked like family. But while Bernstein in the 1940s was raging at the world to stop destroying itself in his Symphony No. 1, Klein was deep within the Terezín walls, looking for resolution.

At one point, Ullmann wrote, “If genius means fighting the battle of existence against oneself instead of against others — the battle of the genius against the demon — then to be a mystic is to have fought this battle and won.”

Whatever they were, the composers had to turn inward to find a safe place — a creative place where music was possible. Does that make them mystics by necessity?