In the midst of the filth and deprivation of a concentration camp, Etty Hillesum remained a celebrant of life.

A few years ago I went to Auschwitz, the notorious Nazi death camp and the focal point of the worst atrocity of the 20th Century. It is a very disturbing place—even our guide seemed depressed—and as I walked around the site I was consumed with its dark history.

And yet at the same time I was also aware that this was just a patch of land in the Polish countryside—that grass grew here the same as anywhere else, birds sang in the nearby trees; that life went on, in other words, indifferent to the misery the place had once witnessed.

In September 1943 a young Jewish woman brought here as part of the Final Solution seemed to grasp this bigger context in an extraordinary and far-sighted way. Her name was Etty Hillesum and during the war years she underwent what we would now call a spiritual awakening.

Like her contemporary Anne Frank, she lived in Amsterdam and wrote a diary in which she documented her inner shift from a bourgeois woman plagued by neuroses and self-doubt to someone who, in the midst of the filth and deprivation of a concentration camp, could gaze towards the sky crying “tears of deep emotion and gratitude”.

Even if you have no religious inclination, her story is still a remarkable testament to the human capacity for compassion and awareness in the face of overwhelming horror. And at a historical moment when the political beliefs that led to the Holocaust seem to be undergoing a renaissance in much of the West, her message of love above all else seems more vital than ever.

Her diary, written in tight scrawl on eight exercise books, spanned the years of 1941 and 1942, a time when Holland was under Nazi occupation. She began writing it not long after starting therapy with Julius Spier, a German Jew who had abandoned a profitable career as a banker to read palms and study analysis at the feet of Carl Jung.

It is clear from the diaries that Etty developed an obsession for Spier, who seemed to encourage the relationship via some sexually-charged therapeutic techniques that look questionable by today’s standards.

But it’s also clear that Spier was instrumental in Etty’s personal growth. Part of what Spier seemed to have led her to was a greater appreciation of living in the present moment, a core idea of mystics of all religious persuasions for many centuries and one that is finding new currency now via the mindfulness movement and spiritual thinkers like Eckhart Tolle.

On 21 March 1941, for example, she writes: “In the past I would live chaotically in the future, because I refused to live in the here and now. I wanted to be handed everything on a platter, like a badly spoiled child… I simply refused to do what needed to be done, what lay right under my nose. I refused to climb in to the future one step at a time.”

This is one of many moments when the diary can seem deceptively modern. Another is this entry from 4 August 1941 offering a clear-sighted appraisal of the struggles of being a woman that anticipates the feminist movement by more than two decades.

“Sometimes, when I pass a woman in the street, a beautiful, well-groomed, wholly feminine, albeit dull woman, I completely lose my poise. Then I feel that my intellect, my struggle, my suffering, are oppressive, ugly, unwomanly; then I too want to be beautiful and dull, a desirable plaything for men… Perhaps the true, the essential emancipation of women still has to come. We are not yet full human beings; we are the “weaker sex”… We still have to be born as human beings; that is the great task that lies before us.”

Her modernity is also evident in the way she constructed her belief system. Like many contemporary spiritual seekers she borrowed from a mish-mash of sources—the poetry of Rilke, Sufism, the teachings of Christian mystics like Meister Eckhart and St Augustine. When she was searched by guards on her arrival at Westerbork, the Dutch transit camp from where she was eventually taken to Auschwitz, they found copies of both the Koran and the Talmud in her bag.

The result of her spiritual journey was a growing inner peace that allowed her not only to accept the horrible truth of what was happening to her people, but to thrive in spite of it. On 3 July 1942 she wrote: “Very well then, this new certainty that what they are after is our total destruction, I accept it. I know it now and I shall not burden others with my fears… I work and continue to live with the same conviction and I find life meaningful, yes, meaningful.”

It might seem perverse that someone could find life meaningful amid the senseless horror of the Holocaust but Etty was one of those rare individuals able to live through history and outside of it at the same time. This is one of the reasons why she is such a great chronicler of what happened.

After resisting several attempts by concerned friends to take her in to hiding she eventually found herself in Westerbork, first as a volunteer social worker and finally as an inmate. The stronger she grew in her faith the more convinced she became of the importance of “never shutting your eyes to reality” and the letters she was able to get out of Westerbork are truly devastating portraits of the appalling inhumanity of concentration camp life.

Especially hard to read are her accounts of the weekly loading of trains bound for the camps in Poland. By this point everyone knew that the journey east meant certain death and the night before the trains set off was fraught with tension as inmates waited to see if they would be sent.

She describes an encounter in the hospital barracks with a paralysed young girl. “’Have you heard? I have to go.’ We look at each other for a long moment. It is as if her face has disappeared; she is all eyes. Then she says in a level, grey little voice, ‘Such a pity, isn’t it? That everything you have learned in life goes for nothing.’”

At times the heaping on of atrocity stretches even her faith. She describes seeing the “ash-grey, freckled face of a colleague” beside the bed of a dying woman who has swallowed poison and “who happens to be her mother”. “’God Almighty. What are You doing to us?’ The words just escape me.”

And yet through it all she never gives in to hate, never gives up believing in life’s ultimate beauty, even as the world caves in around her.

In one of her last letters to her friend Maria Tuinzing, written a week before she was put on a transport east along with her parents and brother, she wrote that “we have become marked by suffering for a whole lifetime. And yet life in its unfathomable depths is so wonderfully good, Maria—I have come back to that time and again.”

Etty died in Auschwitz two months later on 30 November 1943. She was 29.