Cell Theory

Infectious diseases were familiar in early periods and it was considered that they spread by contact, even though no one knew exactly how this happened. Epidemics occurred and frequently spread - the Black Death in 14th century Europe is a well-known example - and this perpetuated the widespread belief in many societies that they were due to paranormal causes. Undeniably epidemics were often considered to be divine punishments. The first definite suggestion of a scientific …

…body against attacks by "foreign" invaders, like germs, that can cause illness. Under normal conditions, your immune system protects your body from diseases and infections by killing these harmful "foreign" substances that enter the body. The cell theory has relieved our battles of illness and showed us a simpler way of treating disease and recognize different diseases that contain different types of cells. We can now cure illnesses and identify them simply with a microscope.