Astrology has had a profound influence over the past few thousand years on Western and Eastern cultures. In the middle ages, when even the educated of the time believed in astrology, the system of heavenly spheres and bodies was believed to reflect on the system of knowledge and the world itself below.
Astrology has had an impact on both language and literature. For example,influenza, from medieval Latin influentia meaning influence, was so named because doctors once believed epidemics to be caused by unfavorable planetary and stellar influences. The word "disaster" comes from the Latin dis-aster meaning "bad star". Adjectives "lunatic" (Luna/Moon), "mercurial"(planet), "venereal"(Venus), "martial"(Mars),"jovial"(Jupiter), and "saturnine" (Saturn) are all old words used to describe personal qualities said to resemble or be highly influenced by the astrological characteristics of the planet, some of which are derived from the attributes of the ancient Roman gods they are named after. In literature, many writers, notably Geoffrey Chaucer and William Shakespeare used astrological symbolism to add subtlety and nuance to the description of their characters' motivation(s). Often, an understanding of astrological symbolism is needed to fully appreciate such literature.