Basic objective of this lecture is to present on Louis Pasteur and Germ Theory. People knew there was a link between dirt and disease, but could not explain the link. People explained disease as seeds bad seeds in the air known as miasma. 1850s and 1860s breakthrough in the cause of disease. Old Germ Theory: spontaneous generation; micro-organisms are the result of decaying matter. New Germ Theory: germ theory; micro-organisms cause decaying matter. Pasteur showed you could kill the micro-organisms by applying heat – Pasteurization.