From the spinning wheel, to plentiful rags, to cotton paper, to the printing press.-

> ADDED: The Romans did apparently have some knowledge of antibiotics

Fascinating. Worth looking into.-

Sometimes, all it took was one person noticing something (midwives who wash their hands post partum tend to have better outcomes, farmers near cows get less sick, or not at all ...)

... but, you raise another good point: First principles, the search for the facts. Benefits at scale come with, consistently, wanting to go from observation, to general principles, to particular application, to mass application ...

... and, maybe, it took rational thought and the scientific method to get there.-