Academy of Sciences of Heroesland

It wasn't obvious. It was believed that Galilean transformations applied to light.

I'm not talking about what was believed a certain number of years ago, but about the fact that the speed of light does not exceed 300,000 km/s, and it's interesting to know where this speed came from.

And even earlier, it was believed that light propagated instantaneously.

And even earlier, it was believed that the Earth was flat and the sun revolved around it.