Medieval scholars attributed a variety of medical powers to smell. Doctors used their sense of smell to judge the qualities of medicines and diagnose illness. In general, good odor could heal the body and prevent illness, while stench was a cause of disease. Good odors, as fumes, were similar to the body’s fumous spirits, which supported the function of the organs. Their similarly fumous nature allowed odors to nourish the spirits, which late medieval authors considered to be enough of a boost to the body’s health that humans could live on odors for a short time. The effects of smells on the spirits also allowed odors to affect various organs, which is famously seen in the treatment of uterine suffocation by odor. Headache and other illnesses of the brain, including mental illness, were also treated with odors. Although some of these powers have been widely acknowledged as being part of medieval belief, they cannot be fully understood without taking into consideration scholastic theory about the nature of odor and the working of the olfactory sense. Once medieval theory is considered, the capabilities of odors to affect the body become logical and the uses of odors by medieval physicians become predictable.