When I enter a forest of tall fir trees, reaching toward the sky, I am surrounded, right and left, by their trunks, which seem to me like innumerable columns. Around me, one and the same vertical line is repeated endlessly. Th the extend that these tree trunk are clearly distinguished from a murky background, to the extent that they are well delineated from the blue sky, I am impressed with a feeling of unity, of parallelism.