If you will experiment and draw your conclusions there is a high chance that you will notice or discover something!
What made the apple fall down?
There is no black bile or yellow bile!
Blood is pumped by our heart not our liver!
During 1561 to 1642 the scientific method was invented by Sir Francis Bacon, which encouraged scientists experiment and draw their conclusions. this led to the creation of the experimental method.
Issac Newton filled in the parts that Kepler and Galileo had left out in their theories, he invented 3 Laws of motion, discovered and defined gravity and did many other interesting things that contributes to science.
Andreas Vesalius and William Harvey completely changed people's understanding of the Human body in the 16th century. Andreas dissected humans and described the structure of the organs and William showed that the heart was the centre of the circulatory system along the veins and arteries.