This work is a composition in two parts. The same magic square is transposed in two versions. One can be experienced by the eyes, the other one by the ears. A magic square is a series of numbers arranged in a square grid so that the sum of each horizontal and vertical row and of the corner diagonals is always the same. Magic squares reveal harmony of number and refer to the nature of existence and a cosmic order dominated by mathematical regularity. Number is the origin of all things, Pythagoras said, and Boethius said music is numbers made audible. Presented as a room installation, A magic square of 5 to look at is a floorpiece of 5 x 5 m, and A magic square of 5 to listen to can be heard through a quadraphonic sound system, performing the four staffs of the score independently, starting about 5 seconds after each other. The audience moves around the floorpiece in the space. Panhuysen (1934) is an internationally recognised artist. Best known for his site-specific long string installations all over the world, he also is involved in systematic visual art. Calculus links his visual and sound art together. Furthermore he has been the artistic director of Het Apollohuis for about 2 decades. - Plinkity Plonk.