Buried treasure is a powerful symbol in stories across the ages. From the thrilling adventures of Robert Louis Stevenson's Treasure Island to the outright silliness of the search for the Holy Grail in Indiana Jones and the Last Crusade.

It's not just in fiction – it's a theme in the real world too. We marvel over the discovery of long lost items ranging from Disney Films to ancient fortresses.

But there is nothing quite so wonderful to my mind as when something more precious than gold is uncovered. Namely, previously unknown art, music or writing from a much loved artist, musician or writer.

The joy of discovering new work from a cherished source is especially profound if that person has died and therefore the only chance of finding something 'new' by them is the discovery of previously unpublicised work.

This week it was announced that just such an opportunity will arise next year. 2016 marks the 20^th anniversary of the untimely death of Henri Nouwen – widely regarded as one of the most profound and influential spiritual writers of the 20^th Century.

Nouwen was a Dutch Roman Catholic Priest whose work and writing took him around Europe as well as North and South America. He was only 64 when he suffered a sudden heart attack and died.

His influence and impact reached well beyond his native Europe and far wider than his Roman Catholic roots. Protestants, evangelicals and Orthodox believers all found solace and insight in his books and other spiritual writings and as such, the announcement that there is more to come from his pen despite his early demise has been met with some excitement.

Nouwen's masterwork is The Return of the Prodigal Son. In it he details the life-changing effect of Rembrandt's picture of the famous story of Jesus. He retells the many hours he spent in awestruck wonder in front of the picture before detailing the deep theological insight it gave him. He tells of the almost overwhelming sense of love, grace and forgiveness that he experienced while contemplating the picture, Jesus' story and the implications that had for God's endless love for him.

If describing Nouwen as a 'spiritual writer' has makes him sound warm and fuzzy, he isn't. Consider this passage from The Return... "When Jesus speaks about the world, he is very realistic. He speaks about wars and revolutions, earthquakes, plagues and famines, persecution and imprisonment, betrayal, hatred and assassinations. There is no suggestion at all that these signs of the world's darkness will ever be absent. But still, God's joy can be ours in the midst of it all. It is the joy of belonging to the household of God whose love is stronger than death and who empowers us to be in the world while already belonging to the kingdom of joy."

His other popular books included The Wounded Healer, in which he gave insights for those in ministry and Life of the Beloved: Spiritual Living in a Secular World – which was originally written for a Jewish friend and simply yet beautifully explains his faith.

In The Wounded Healer Nouwen says, "Experience tells us that we can only love because we are born out of love, that we can only give because our life is a gift, and that we can only make others free because we are set free by Him whose heart is greater than ours. When we have found the anchor places for our lives in our own center, we can be free to let others enter into the space created for them and allow them to dance their own dance, sing their own song and speak their own language without fear."

His simple yet gripping writing style belies his training as an academic theologian. He was supremely skilled in that regard – teaching at world-class universities such as Yale and Harvard.

Yet to think of Nouwen merely as an academic and writer would be to undersell his impact. He was a priest who took seriously the vocation to be a servant-hearted leader. This took him to poverty-stricken parts of South America, where he was very far outside his comfort zone. Yet still, he ministered to those he found on the margins.

Away from the university environment and back in a western context, Nouwen was to find his true calling and his home for the rest of his days. At the invitation of the inspirational Jean Vanier, Nouwen went to experience L'Arche – the group Vanier had founded where people with profound disabilities are a key part of the community and live alongside their carers.

Nouwen had found his calling and thrived at L'Arche. So much so that he became the chaplain to one of the community's Canadian branches, and never left. He certainly didn't find life at L'Arche easy. But it inspired some of his finest work and was the culmination of his life's mission – to seek Jesus and to make people aware of God's love for them. A life cut short, maybe, but a life well lived.

In a passage which took on extra resonance from Life of the Beloved after he died, Nouwen wrestled with his mortality, "Am I afraid to die? I am every time I let myself be seduced by the noisy voices of my world telling me that my 'little life' is all I have and advising me to cling to it with all my might. But when I let these voices move to the background of my life and listen to that small soft voice calling me the Beloved, I know that there is nothing to fear and that dying is the greatest act of love, the act that leads me into the eternal embrace of my God whose love is everlasting."

We're told that the first in the new series of books will be based on some of Nouwen's thousands of letters. The editor of the projects says, "I've chosen letters where Henri is responding to people who are in some form of crisis and are looking for direction... I've also chosen letters in which he is struggling with similar issues to the ones that he is responding too." This is what makes the announcement of new material from Nouwen so exciting. His spiritual guidance, careful reflection and inspiration has been a help on the journey for millions of Christians worldwide. Now we have the chance to hear God speak to us through more of his work.

What a joy. In the truest sense of the term – we have found some buried treasure.