The definition of hygiene, or personal cleanliness, has varied from culture to culture throughout history. However, one thing is clear: contrary to popular belief, people have not become cleaner over time. Many factors, including local customs, the outbreak of disease, scientific knowledge, and religious beliefs, have affected the ways people clean their bodies and clothes and dispose of their wastes.
The idea of regular bathing as an important part of personal hygiene is not a modern one. Ancient Romans bathed themselves regularly in large public baths before the first century C.E. In Europe during the Middle Ages (c. 500–c. 1500) there were also many public bath-houses, called "stews" by the common people who used them. In the early 1300s some European monks, men who dedicated their lives to the Catholic Church by joining religious orders, had plumbing that brought water for bathing inside the monasteries where they lived. However, the bubonic plague, a very contagious, often fatal bacterial disease which swept much of the world during the fourteenth century and was also known as the Black Death, caused the closure of many public gathering places, including the public baths. People believed that public baths may have caused the disease, inspiring in many Europeans a fear of using water to clean the body. Some Christians had long believed that submerging the body in water could wash away the holy water of the baptism ritual. After the arrival of the plague, this mistrust of water increased. Many people believed that placing water on the skin would open the pores, allowing disease to enter the body. Alongside these superstitions there was good reason to doubt the safety of water. During the 1400s and 1500s plumbing was fairly primitive and, in large cities, sewage flowed down streets and gutters in open streams that smelled bad and carried disease. Even the water from wells could be contaminated, and no way to purify such water had yet been discovered.
Rather than washing in water, the preferred way of cleansing the body during the sixteenth century was to wipe it with white linen cloths, which were thought to have healing properties. The poor had little linen and no servants to keep it clean and white. They also had little leisure time for bathing or washing clothes. It became common among the poor to bathe only twice a year, once in the spring and once in the fall, though the face, hands, and teeth were usually cleaned daily. The teeth were usually brushed with a chewed twig, then wiped with cloth. The wealthy bathed more frequently, sometimes weekly or monthly. In addition, their servants kept them supplied with clean white linen, both to wipe their bodies and to wear. While most nobles wore clean linen every day, other clothes were seldom washed. The very wealthy simply gave away their clothes when they were too dirty to wear.
Soap had been invented in the Orient and brought back to Europe during the eleventh century by soldiers returning from the religious Crusades to extract control of the Holy Land from the Muslims who lived there. The new soaps were expensive, however, and even the king seldom used them. Instead, most of the royalty and nobility concealed the smell of imperfectly cleaned bodies with a variety of strong perfumes. Most wealthy people carried bottles of perfume, pomanders (scented jeweled balls), or scented handkerchiefs with them at all times. The poor simply smelled.
The idea that germs cause disease and infection, and that cleanliness can prevent the spread of germs, was not widely understood until the 1800s, but a sixteenth-century French doctor named Ambroise Paré (1510–1590) did discover the value of cleanliness in treating wounds. On the battlefield Paré ran out of boiling oil, the usual treatment for soldiers' wounds, and treated his remaining patients by simply washing their wounds with water. When he discovered that the washed wounds healed, while those treated with oil got worse, he spread the word. Doctors throughout Europe soon stopped using the boiling oil treatment in favor of water.