Scelsi remained largely unknown for most of his career. A series of concerts in the mid to late 1980s finally premiered many of his pieces to great acclaim, notably his orchestral masterpieces in October 1987 in Cologne, about a quarter of a century after those works had been composed and less than a year before the composer's death. Scelsi was able to attend the premieres and personally supervised the rehearsals. The impact caused by the late discovery of Scelsi's works was described by Belgian musicologist Harry Halbreich: