From LaB YouTube Channel Hippocrates, and later Galen, created a framework to explain illness based on four "humors" (vital liquids). https://youtu.be/jbL0T0GE4eg

How common are parasites? How does someone get infected? How do you measure the burden of these diseases? These are a few questions I attempt to address in this brief overview. https://youtu.be/ZLldAY2zNdo

This paradigm-shifting experiment showed that traits could be passed from dead bacteria to living bacteria by some unknown "transforming principle". https://youtu.be/YFmgI2lOGrU