Some years ago I asked myself, whether it was possible to compose a piece built only on 4 different pitches, a piece, in which the listener would hear not only four pitches, but also sound and silence in perfect harmony, music, in which technique wolud become secondary to an invisible mass filled with spirituality. It is challenge: the composer has to work very strict rules and, at the same time, to operate in a very limited musical space. When the piece is performed at a concert, nobody needs to know what is going on. Only theinvisible mass stays... Boško Milaković