Many cultures have attached importance to astronomical events, and some—such as the,, and —developed elaborate systems for predicting terrestrial events from celestial observations., one of the oldest astrological systems still in use, can trace its roots to 19th–17th century, from which it spread to,, the and eventually. Contemporary Western astrology is often associated with systems of that purport to explain aspects of a person's and predict significant events in their lives based on the positions of celestial objects; the majority of professional astrologers rely on such systems.: 83 Throughout most of its history, astrology was considered a scholarly tradition and was common in academic circles, often in close relation with,,, and medicine. It was present in political circles and is mentioned in various works of literature, from and to,,. Following the end of the 19th century and the wide-scale adoption of the, astrology has been challenged successfully on both: 249; and grounds, and has been shown to have no scientific validity. Astrology thus lost its academic and theoretical standing, and common belief in it has largely declined.