The Stars and planets
Medieval astrologers believed that the movements of the stars influenced numerous things on earth, from the weather and the growth of crops to the personalities of new born babies and the inner workings of the human body. Doctors often carried around special almanacs (or calendars) containing illustrated star charts, allowing them to check the positions of the stars before making a diagnosis. Many of these almanacs included illustrations, helping to explain complicated ideas to patients. The picture below shows a 'zodiac man' from one of these almanacs from 1399. The diagram was intended to explain how the astrological formations (or star signs) rule over each part of the body. The man's pointing finger serves as a warning against the powerful forces of the stars.
Ancient studies of astrology were translated from Arabic to Latin in the 12th and 13th centuries and soon became part of everyday medical practice in Europe. By the end of the 1500s, physicians across Europe were required by law to calculate the position of the moon before carrying out complicated medical procedures, such as surgery or bleeding.

A diagram known as the 'Zodiac man' superimposed the appropriate star sign onto body parts; in a manuscript owned by the Barber Surgeons of York, this diagram faces a circular wheel marked with astrological data and equipped with a moving pointer (known as a volvelle) so that the physician could align the data according to the position of the sun and moon.
The barber surgeon was one of the most common medical practitioners of medieval Europe - generally charged with looking after soldiers during or after a battle. In this era, surgery was not generally conducted by physicians, but by barbers.
They often took up residence in castles where they also provided medical assistance to the rich and wealthy.
Examining urine
One of the main ways in which a physician would diagnose illness was by examining stools, blood and especially urine: