The humoral theory comes from an ancient Greek theory that states that the human body is composed of four basic humors. The Humoral theory is derived from the word “humor,” but in this context, means “fluid”. The Humoral theory is related to the theory of the earth and the four elements. These elements are better known as earth, fire, water and air. The balance in these earthly elements allows the earth to sustain human life. These four basic humors of the Humoral theory consist of black bile (known as melancholy), yellow bile, phlegm and blood. These four basic humors act as the basis that helps us to determine the health of an individual. According to this ancient theory, the four humors must be in balance for the body to be healthy (homeostasis). If an individual has an excess or is deficient in one of the humors this imbalance results in disease or the disability in the physical health or mental health of an individual.
In (1682 – 1771) an Italian physician named Giovanni Battista Morgagni did an in depth study of the Anatomical Concepts of Disease. In this study Dr. Giovanni found a connection between a patient’s visible symptoms and pathology. This theory lead him to a link between the patient’s physical signs and what was happening in a patient’s internal organs. It was a new concept that believed that because blood flowed throughout the body that therefore blood could carry disease through the body and organs.
The germ theory was made possible by the advent of certain laboratory instruments and techniques that enabled the study of bacteria and microorganisms during the seventeenth and eighteenth centuries.