The scientific method
is a decidedly modern invention. Ancient scientists had no notion of it, and for the most part preferred thought-experiments and theories based on everyday observation
There were a few exceptions to this, however, the most famous being the linguistic experiment performed by King Psammetichos, ruler of Egypt, in the 7th century B.C. (Can you imagine getting this by the ethics committee today?)
According to Herodotus, King Psammetichos wanted to prove (a revolutionary concept in itself) that Egyptian was the world's oldest language. To do this, he had two infants placed in the isolated care of shepherds who were forbidden to speak. The idea was to see what language the children would spontaneously start speaking in the absence of being taught. When the children started to speak, their words were recorded and ambassadors were sent around the world to find out in what language the word for bread was "bekos" (because it wasn't Egyptian). Based on his findings, Psammetichos concluded that Phrygian was the oldest language.
James IV of Scotland and Akbar Khan also repeated the experiment, though I'm not sure what their findings were.