The art of copying nature is suggestive of the perpendicular line, which represents all between heaven and earth. Also the perpendicular line denotes concentration and observation, the higher point of the line showing heaven, the lower part the earth. It is the straightness of glance in copying and the steadiness of the impression of nature which the artist gets that are both symbolized as the straight line. Therefore the ancient mystics have called the straight line "alif," which means first, the origin and source of all things. The word "alpha" comes from the same root.