One day, flutist Eleonore Pameijer, founder of the Leo Smit Stichting, received a package in the mail. It was her birthday and she opened it with great curiosity. It contained a music manuscript, with a note by Ima Spanjaard-van Esso. 'I heard about the Leo Smit Stichting on the radio and thought this should go to you.'

In her youth, Ima van Esso was a very pretty girl. She had many admirers, even without realising it. Dick Kattenburg too had fallen in love with her. He composed a sonata for Ima, who was a flutist. Ima accepted the work in gratitude, but never studied it. Three years later, war broke out. Dick went into hiding, but was arrested. He was killed in Auschwitz only 24 years old. Ima survived the horrors of the concentration camps. She never touched her flute sonata. At the end of her life, she decided that Eleonore Pameijer should have the manuscript. When Ima received a cassette tape in the mail after a few weeks, she cried. 'Now I understand, it was a love letter.'

The love letter did not go unnoticed. While browsing the internet, Joyce Bergman-van Hessen, the daughter of Dick's sister Daisy, discovered an announcement of a concert including her uncle's flute sonata. She remembered a box of music sketches in the estate of her late mother and immediately went up to the attic. A considerable number of chamber music compositions by Dick Kattenburg were premiered at the Uilenburg Concert Series. Today, twelve compositions by Dick Kattenburg have been recorded on CD and his music is performed by musicians all over the world.

In 2009 FutureClassics released a CD with chamber music by Dick Kattenburg.