Please forgive me if I missed it and don't be mad at me for having to explain it. I'll understand if you don't want to take the time.
Shalom.
It was previously thought that things could supernaturally form from matter. For example, if you put cheese and rags in a box, baby mice would spontaneously form from the rags in the box. Obviously, people built tighter airtight iron boxes, and found that mice only came from mice.
However, this did not prove conclusively that life did not spontaneously, supernaturally form. Pasteur proved that was the case in his experiment.
So, this is an example of how a supernatural explanation for an observed phenomenon could be proved invalid. Over the course of the 19th century, it became more and more obvious that any explanation that included supernatural causes were not science.
Some questions answered in the 19th century:
1) How old is the earth?
2) Where does life come from?
3) Why do people get sick?
These questions were starting to be answered by assuming that supernatural explanation were invalid. Assuming otherwise gets you these answers:
1) 6000 years old
2) God created life
3) Poor balance of humors