Ptolemy was concerned to defend astrology by defining its limits, compiling astronomical data that he believed was reliable and dismissing practices (such as considering the numerological significance of names) that he believed to be without sound basis.
Ptolemæus var bekymret for at forsvare astrologien ved at definere dens grænser, samle astronomiske data, som han mente var pålidelige og afvise praksisser (fx overvejelser om numerologiske betydning af navne), som han mente var uden sund basis.