It is often assumed that the Greeks invented mathematics in the 5th century BCE, and that they had a set definition of what it entailed. But this is an over-simplification of the history of mathematics.
The Hippocratic Oath is used to this day as a marker of medical diligence and responsibility, and it is assumed that its author was none other than Hippocrates, the “father of medicine”.
It is a commonplace to believe that people in the past held that the Earth was flat. But already in the distant past, people realized that our world is spherical.