Astrolabes captured not only the motions of the sun and stars but their influence too. There was no clear separation between astronomy and astrology at the time the instrument was current: astronomers were routinely expected to cast horoscopes. Equally, medieval physicians interpreted and predicted disease using the zodiac and the planets. Since the astrolabe could be set to any time or date, it could save a great deal of time and tedious calculation. So it is not surprising that astrolabes are found with further features specially designed for astrological use.