"Let us define the job of the astronomer in the classical phrase as "saving the appearances" of the celestial movements. ...[A]n astronomical theory must "save" in the sense of "preserve"– ...[i.e.,] it must not deny any of the apparent celestial movements as appearances, and in this bare sense, it might merely comprise a record of observed positions... [I]n order to take into account all the apparent movements, it must... predict apparent movements in the future from those observed in the past. ...[T]o be able to look backwards and forwards beyond recorded positions of the planets, it must arrange the celestial movements in a pattern of orderly recurrence. ...[B]y setting up this pattern of order, it saves... in a second sense... [I]t gives them salvation... by making them intelligible and... explicating them in terms of a permanent order."