The Sabian symbols belong wholly to twentieth-century astrology, though they draw on an older tradition of degree symbolism reaching back through several earlier sets. Their interest lies in how a fixed, evocative image for each degree is used interpretively, and in the two influential versions, Jones's and Rudhyar's, that circulate.
The atlas treats the symbols as a modern system with a datable origin, describing how they are used and giving the images. They sit within the degree-level tools of Western astrology alongside the decans.