A fine horizantal straight black line runs over small pieces of whitened cardboard. Some time the line runs from one side to the other, some time it starts from one side, but goes only half the way. On 24 plates, on each on four levels, such lines are playing out all possible variations and might function as a preposition. Defining the spatial location and arrangement of some object. 'Algebra of Prepositions': through, in-out, of-from, in, varies the linear transcription of four prepositions visually on the small image boards.