It was in a Nazi prison camp during World War II that 22-year-old Hans Rookmaaker read the Bible and became a Christian. It was there too he received his first instruction in the Neo-Calvinist philosophy of Dooyeweerd by an older fellow prisoner, J.P.A. Mekkes. And it was there the young Rookmaaker started writing his Sketch for an Aesthetic Theory based on the Philosophy of the Cosmonomic Idea. The philosophical writings brought together in the second volume of the Complete Works show the Dooyeweerdian roots of Rookmaaker's art-historical work, an essential insight for a proper understanding of his philosophical framework. After the war, Rookmaaker returned to academic life and opted to research art history as his 'mission field', but only after seriously considering the field of musicology first. Rookmaaker loved music, especially jazz, blues, spirituals and black gospel music, his lifelong interest and lively enthusiasm are expressed in the book and articles included here.