Educated men (and those of the 1200s through the 1500s), believed that the earth was the center of the universe and that it was surrounded by a giant spherical dome on which the stars were placed. The sun and moon and planets were each on a sphere around the earth that was responsible for their movements. The origin of the word "planet" meant "wanderer" because the motion of the planets changed in direction and speed. Astrology explained how the position of the stars and planets influenced man and other earthly things. For instance, the position of the stars at a person's birth determined his character. The angle and therefore potency of the sun's rays influenced climate, temperament, and changes of mortal life such as disease and revolutions. Unusual events such as the proximity of two planets, a comet, an eclipse, a meteor, or a nova were of great significance. A star often was thought to presage the birth of a great man or a hero. There was a propitious time to have a marriage, go on a journey, make war, and take herbal medicine or be bled by leeches, the latter of which was accompanied by religious ceremony. Cure was by God, with medical practitioners only relieving suffering. But there were medical interventions such as pressure and binding were applied to bleeding. Arrow and sword wounds to the skin or to any protruding intestine were washed with warm water and sewn up with needle and silk thread. Ribs were spread apart by a wedge to remove arrow heads. Fractured bones were splinted or encased in plaster. Dislocations were remedied. Hernias were trussed. Bladder stones blocking urination were pushed back into the bladder or removed through an artificial opening in the bladder. Surgery was performed by butchers, blacksmiths, and barbers.