sagan mentioned the ionian enlightenment of about the 6th century bc as an early period of something close to the scientific method. but it gave way to what sagan called the mystics, eventually leading to aristotelian philosophy.
sagan cites a historian who claimed the reason for the decline of science was that science experiments involved manual labor. in the stratified society of greece, manual labor was undignified employment for workers and slaves, however workers and slaves often lack the education and leisure to pursue science. and gentleman and ladies will not want to challenge the status quo with new discoveries.
so science required (and perhaps still requires) an atypical societal structure to flourish.